The improbable Austin comeback that upstaged LMP1

The chances of United Autosports following up on its maiden World Endurance Championship LMP2 class victory in Bahrain in December didn't look likely just after the start of the second hour in Austin last weekend. Paul di Resta had just pitted the team's ORECA-Gibson 07 early with tyre issues and the car was down in eighth place. But, just over four and a half hours later, the machine co-driven by Filipe Albuquerque and Phil Hanson completed an almost comfortable 24-second victory.

A combination of the United trio's speed on a day when its Michelin tyres proved superior to the rival Goodyears and a revised strategy thought up on the hoof allowed the team to overcome the handicap of an extra pitstop caused by early issues. It helped, too, that United's rivals in class each had delays or problems of their own.

Di Resta had jumped into the class lead at the start, but the tyre issues meant he was down in fourth inside 15 minutes. The Scot, back at Austin for the first time since the end of his Formula 1 career in 2013, had started on the softer-compound Michelin rubber on which he and Hanson had qualified second.

There was a secondary issue with tyre pressures, which the team only tacitly confirmed, that explained why the car had slipped to seventh by the first driver change. They combined to force di Resta to duck into the pits 20 or so minutes early to bring a premature halt to his troublesome stint.

The United car quickly returned to the lead of the race, though only because it was out of pitstop sequence with its rivals. It bounced up and down the leaderboard until the final hour, when di Resta found himself with a lead of well over a minute. That was enough for him to duck into the pits with around 20 minutes to go and hang on to the top spot despite a quick stall on his way out.

"We made a bit of a miscalculation on something for the first two stints that meant we had to stop 11 laps early to avoid getting a puncture," said di Resta.

"Once we resolved that, we were always fighting back. It looked like it would be hard to come back but we were strong at the end."

"I'm amazed he didn't get a penalty; he was half off the track when he hit me" Will Stevens on Giedo van der Garde

Albuquerque added: "We were surprised at the pace of some of the others; they were struggling. Hats off to United and its strategy."

The Jota-run, Goodyear-shod Jackie Chan DC Racing ORECA that took second in the hands of Will Stevens, Ho-Pin Tung and Gabriel Aubry didn't have the pace of the race winners. Yet it would have been in a position to benefit from United's late stop but for an early delay of its own: Stevens was tapped into a spin by Giedo van der Garde in the Racing Team Nederland ORECA at Turn 8.

Stevens wasn't best pleased by the move that the team reckoned cost it victory in Texas.

"I'm amazed he didn't get a penalty; he was half off the track when he hit me," said the Briton. "Having to fight back through the field really hurt us on my second stint on the tyres."

If United had a clear edge on the Jota car, then the TDS Racing-run RTN entry in which van der Garde was joined as usual by Nyck de Vries and Frits van Eerd had an even more significant advantage over the pair of them on the lap averages. The all-Dutch crew looked for a while as though they might reprise their Fuji victory, thanks to another stellar performance from de Vries.

The Mercedes Formula E driver pulled back a minute on the leaders after taking over from amateur driver van Eerd at the start of his first double stint, but any chance RTN had of scoring its second win of the season had disappeared by the time de Vries clambered back aboard the team's ORECA for the run to the flag.

Van Eerd struggled in his second stint and was haemorrhaging time, so the team called him in early with the result that de Vries would have to make a splash-and-dash fuel stop at the end. He briefly looked as though he might have a sniff of making it back into the podium positions as he closed on Anthony Davidson in the Goodyear-sponsored ORECA that Jota runs under its own name.

Not only is United Autosports mounting its first full-season WEC campaign, but it made a last-minute switch to the ORECA from the Ligier JSP217

That was until the he ran out of grip: the Michelins on the right-hand side of the car had done two and a half stints by the end of the race.

Such was the drop-off of pace from the RTN car that de Vries was caught and passed for fourth by Nicolas Lapierre in the Cool Racing ORECA that he and Antonin Borga had put on pole. The Silverstone class winners were as usual compromised by amateur driver Alexandre Coigny's pace.

The tyre problems for RTN allowed Davidson, who shared the second Jota car with Antonio Felix da Costa and Roberto Gonzalez, a relatively stress-free run to the flag in third place, though they ended up a lap down on the sister car. Davidson and da Costa were a match for their professional team-mates, but Aubry had a clear edge over Gonzalez.

The fastest LMP2 over the course of the Lone Star Le Mans event in Austin could only finish an unrepresentative sixth.

Signatech Alpine, last season's LMP2 champion team, finally had a competitive car for the first time of the 2019-20 campaign, but Andre Negrao, Pierre Ragues and Thomas Laurent lost out on any chance of a decent result when the right-front brake disc exploded in the second hour.

Ragues was on his second lap out of the pits and had just taken the lead from the RTN ORECA when the failure occurred at the end of the long back straight. The five minutes or so that the car sat in its pit undergoing repairs cost Signatech more than two laps to the class leader and left its drivers no way back.

"This is very disappointing because we have got the pace back," said Ragues. "The guys have worked hard since Bahrain, so we have to focus on the positives. We're off to a good start in 2020."

Signatech's chances to retain its title are looking more difficult by the race and it has now slipped 30 points off the class lead. United's second consecutive victory means that Albuquerque and Hanson now head the championship by four points (di Resta missed Fuji courtesy of a DTM clash so is down in third) from the Chan/DC drivers.

The context of United's rise to the top of the pile makes it all the more impressive. Not only is the team mounting its first full-season WEC campaign, but it made a last-minute switch to the ORECA from the Ligier JSP217.

"We had quite a few issues with the new car that kind of delayed our first victory," said Hanson. "Since we've resolved those issues we have showed our true strength. Hats off to the team."

TF Sport Aston makes it three in GTE Am

The British TF Sport Aston Martin squad bounced back from a retirement in Bahrain in December to make it three wins from the past four races in the 2019-20 World Endurance Championship. Charlie Eastwood, Jonny Adam and Salih Yoluc followed up on their Shanghai and Fuji victories with their hardest-fought win yet.

The winning Vantage GTE and the factory-run Aston shared by Darren Turner, Ross Gunn and Paul Dalla Lana were locked together for most of the way at Austin, the TF car having to come from behind twice to seal the victory.

Yoluc lost time during his opening double stint when he had a coming-together with Dalla Lana. Adam got ahead of old team-mate Turner in the fourth hour, and then Eastwood had to do it all over again after being jumped by Gunn in the final round of pitstops.

Gunn was given two new tyres, whereas Eastwood took on four, which explained why TF's advantage of just over four seconds turned into a similar deficit as he came out of the pits. The two Astons were nose to tail a third of the way through the final stint and battled hard for the next third, before Eastwood found a way through and eked out 3.7s before the chequered flag.

"In my first stint, I left the pits 4.5s ahead of Ross and came in with 4.5s, so we were doing the same pace all the way through," said Eastwood. "It's always a sinking feeling when you see the other car drive past while you are still sitting in the pits, but it gave me motivation to push a bit harder."

Third place went to the Project 1 Porsche in which Michelin Le Mans Cup champion Laurents Horr has replaced David Heinemeier Hansson alongside Egidio Perfetti and Matteo Cairoli. Fourth place for AF Corse Ferrari drivers Emmanuel Collard, Nicklas Nielsen and Francois Perrodo was just enough to maintain what had been a joint championship lead (with Project 1 drivers Ben Keating and Jeroen Bleekemolen) over the TF Sport trio.

Rebellion's win not as easy as it looks

Rebellion Racing looked as though it had things more or less to itself at the head of the paltry three-car LMP1 field at Austin, prompted by Ginetta's withdrawal. But the claim of winning drivers Bruno Senna, Gustavo Menezes and Norman Nato that it wasn't that easy was supported by Toyota.

Had the Rebellion continued at 23 laps, then "we were on to win", reckoned Toyota Motorsport GmbH technical director Pascal Vasselon

The solo Rebellion-Gibson R-13 ended up taking the flag after six hours of racing by an ostensibly comfortable 51.5 seconds as the two Toyotas struggled in the face of success handicaps in excess of two seconds per lap.

But the second win of the season for the Swiss entrant required some serious fuel saving along the way to avoid a late splash-and-dash stop.

That would have brought the second-placed Toyota TS050 HYBRID shared by Sebastien Buemi, Kazuki Nakajima and Brendon Hartley into the picture. The Japanese manufacturer was pretty sure it would have won had the Rebellion had to make a stop for fuel.

"Through the second half of the race Norman and I were really having to take care on the fuel," said Menezes. "It definitely proved to be much tougher than we expected going into the race."

The Rebellion went 22 laps on its first stint and 23 laps on its second with Senna at the wheel. That would not have been enough to avoid refuelling, which explains why, for a big portion of the race, the gap between the top two stabilised at 25 or so seconds as Menezes and Nato stretched their fuel allocation to at least 24 laps.

Had the Rebellion continued at 23 laps, then "we were on to win", reckoned Toyota Motorsport GmbH technical director Pascal Vasselon.

The Toyotas went longer on the fuel and were quicker in the pits, which kept the #8 TS050 notionally in the race. The Japanese manufacturer was unable to play a strategic card, however, because the race was devoid of safety cars.

The #7 Toyota was nowhere. Championship leaders Mike Conway, Jose Maria Lopez and Kamui Kobayashi were penalised by 2.77s per lap compared with the sister car's 2.21s and the Rebellion's 0.55s, but the real gap between the TS050s was a second over the course of the race.

The effect of the penalties imposed on the TS050s - a reduction in fuel flow and hybrid power - isn't linear, explained Vasselon. The further the car is outside its working window the more they take a toll.

"The linear coefficients are correct with handicaps from zero to 1.5s, but going from 1.5s to nearly 2.8s, we face very high non-linearity because you are outside the working point of the car," he said.

"The gap we were expecting between the two cars was one second and we saw that."

That one-second deficit explains why Lopez and his team-mates were two laps down in third at the end of the race despite outqualifying their team-mates. That came from Hartley losing his quickest lap to a track-limits infringement and not being able to recharge the car's battery before needing to set a time in a session that had been interrupted by a red flag.

Aston Martin tightens its grip on GTE Pro

Nicki Thiim and Marco Sorensen led all but six laps in Austin, and were behind only during the first three cycles of pitstops. So it's hard to argue that the Aston Martin duo didn't dominate in GTE Pro, even though the margin of victory was a scant four and a bit seconds.

The Circuit of The Americas has always been a home from home for the British manufacturer in the WEC, and the latest Vantage GTE proved well suited to the track thanks to its high downforce levels and the proliferation of quick corners. Pole position, a first for the car introduced at the start of 2018-19, fastest lap and victory number three of the current campaign were the result.

"I had the feeling they were playing with us a little bit. Every time I got a little bit closer, Thiim pulled away again. It looked easy for them" Michael Christensen

Yet Thiim still had to fight off a late challenge from the Porsche 911 RSR shared by Michael Christensen and Kevin Estre to seal the win. Christensen, who drove two double stints to the pair of singles for his flu-ridden team-mate, reduced the deficit to the leader over the course of the penultimate hour and then forwent tyres when he made his final pitstop. That jumped him from nine seconds behind to just four.

The Porsche did make inroads into the Aston's advantage, a tenth here and a tenth there, though it never came down to much less than three and a half seconds.

"I don't know what's going on at the moment," said Thiim. "It's turning into a really good season where everything is working out fine. The car suits this track really well, and we're looking really good right now."

Sorensen reckoned the victory "was harder than it looked". It would have been harder still had the Porsche not lost time early in hour two.

Christensen took over from Estre, but with the seconds lost taking on new Michelins, the car ended up in among the GTE Ams and then bottled up behind James Calado's AF Corse Ferrari 488 GTE.

"That definitely hurt us," said the Dane. "I had to push quite hard and that cost time during the second half of my stint because I'd worked the tyres quite hard."

But Christensen was in no way claiming that this was a race that Porsche somehow lost: "I had the feeling they were playing with us a little bit at the end. Every time I got a little bit closer, he pulled away again. It looked easy for them."

Ferrari didn't have an easy day in Austin, though Calado and Alessandro Pier Guidi once again salvaged a decent result from a race that didn't appear to be going their way for long periods. Both AF cars were afflicted by an understeer problem that stymied their performance.

"The car was awesome in qualifying, but there was a massive balance shift between yesterday and today [Sunday]," explained Calado. "The understeer was severe, so we need to look at what happened."

Calado was able to sneak onto the podium in the closing stages when he nipped past Alex Lynn in the second of the Aston Martins. Lynn and co-driver Maxime Martin conceded that they rarely had the pace of the sister car last weekend.

The solo Chevrolet Corvette C8.R, making the first of two WEC appearances ahead of the Le Mans 24 Hours, ended up three laps down in sixth in the hands of Jan Magnussen and Mike Rockenfeller. They were never on the pace in a car that was running what can only be called a conservative Balance of Performance: the new Corvette's engine air-restrictor was 6% smaller than the one it ran on its debut in last month's Daytona 24 Hours.