The new stars complicating the DTM title fight

This year the DTM title fight has taken on a whole new complexion. With 2018 champions Mercedes and Gary Paffett switching to Formula E (via HWA) and Merc's other contender Paul di Resta moving to the new R-Motorsport Aston Martin project, '19 was always going to be wide open.

But last year's fight was not exclusively between the Mercedes duo. To suggest that would ignore Rene Rast's mind-blowing run during which he turned the weaker Audi RS5 package into an out-and-out threat to the leading title contenders, winning six successive races to take the championship fight down to the final race and heap the pressure on Paffett.

Putting aside the fact the DTM then switched to Class One regulations once Mercedes exited (which means drivers have to contend with 100bhp more on the 2018-spec Hankook rubber, creating inherent understeer and putting a premium on tyre management), few would have bet against Rast picking up where he left off at the beginning of this campaign.

But the season has now passed its halfway mark, and while both Audi and BMW were quick to shoot down any prospect of team orders enforcement to favour one driver over another so early at Assen last weekend, those thoughts will begin to cross minds.

Audi's team orders were straightforward last year. Rast's imperious run meant it was easy to throw all its resources behind him: he finished second in that year's standings while the second-best Audi driver, Nico Muller, was 10th.

But Assen showed that Audi is going to have much more of a headache in 2019. Muller is now maximising what he considers the "small details" to add much-needed consistency to his driving.

Though it was overshadowed by Rast's run, Muller - still just 27 - made considerable strides last year. Those close to him have suggested he's matured as a driver and he's demonstrated that - most noticeably at last year's Red Bull Ring round, where he twice cooperated to allow Rast to take a clean sweep of the weekend, but was otherwise firmly in contention for victories.

Muller's second DTM career victory at Misano earlier this year proved to be timely. Not only did he end his three-year drought with the Audi Abt squad, but he also showed success could be found post-Mattias Ekstrom, whose exit at the end of 2017 coincided with a downturn in form for the outfit. That Misano win is Muller's highlight, but the Swiss driver is the only contender in the top four to have scored points at every round and has taken six podiums in '19.

"We carried on from where we left off [last year]," says Muller. "I think our run last season was pretty strong as well. Rene - yes, he stood out, but we were not far away at all. It was the last details that made the difference for him and we also could have won races last year, so it's not that we've suddenly found the magic over the winter. We kept working hard and grew together as a team."

Whether "today's setback is tomorrow's comeback" is cheesy or not, Wittmann has applied it to balance disastrous results with three wins - the same amount Rast's far more straightforward campaign has yielded

Those details Muller talks about relate primarily to him gelling with race engineer Felix Fechner, who until last year had never fulfilled such a position in the DTM - he switched from his performance engineer role in the wider Audi DTM group at the beginning of 2018.

"I had a new race engineer last year - he's very young, he's the same age as me and he's never run a car before and he's never been a race engineer," Muller explains. "We really gelled over that last season and the winter time. We're working together very well and we have a great crew of mechanics. [We're] just really enjoying work and I think that's what in the end can make the difference."

Muller's showing at Assen showed the virtue of him and Abt working in unison. An aggressive long-running first stint in the opener lifted him from sixth to third and moved him into victory contention, but Muller lost out when he couldn't get his tyres into the operating window swiftly enough on his outlap, allowing Marco Wittmann to return to the front and eventually claim victory.

Muller has shown great form in making up lost ground this year, but he has to improve his qualifying performances going into the final stages of the season, as he averages a starting grid slot of 5.9 compared with Rast's 3.3. Muller not only needs to nail the crucial first-run qualifying lap, but he and his team need to find the best compromise between qualifying and race trim, since parc ferme conditions prevent modifications to the car between the two sessions.

With just 22 points separating Rast and Muller at the top of the standings, the Abt driver needs to keep the pressure on in the final four rounds to make Audi's team-orders dilemma all the more challenging.

Audi's stress is coming from another angle, too, for while it appears to have an edge over BMW, two-time champion Wittmann remains a threat.

Wittmann has had a wildly up-and-down season. He was eliminated in a clash between Rast and the WRT Audi of Jonathan Aberdein at Misano, lost a potential fifth place with a technical failure at the Norisring, and picked up a penalty for colliding with Robin Frijns at Zolder. But whether "today's setback is tomorrow's comeback" is a cheesy line or not, Wittmann has applied it throughout 2019 to balance those disastrous results with three victories - the same amount as Rast's far more straightforward campaign has yielded.

Wittmann's Norisring weekend hurt, he's made no secret of that, as he scored just four points at his home round thanks to a retirement and a failed strategy gamble. But rather than let it spiral, Wittmann overcame another new set of problems to leave Assen with more points (46) than any other driver and push himself further into the title reckoning.

His weekend began with a car he felt was continually misbehaving in practice on the Friday. But Wittmann worked with his BMW RMG crew to make sweeping changes overnight that yielded pole position in the dry, before going on to take victory in the torrential conditions of the first race.

Not only did he hold off a quicker Rast through Assen's technical, slower first six corners, where the Audis extracted more tyre performance early on, he then used BMW's habit of enjoying more performance from the tyre later in the stint to pull a gap to Rast. When Muller went off-piste on strategy and emerged ahead, Wittmann didn't panic and waited for the cold tyres on the Audi to help open the door for him to move past.

With the maximum 28 points in the bag, given Wittmann's rapidly changing fortunes this season it shouldn't have been a surprise to then see him on the back foot again on Sunday morning when a turbocharger problem left him 18th on the grid. But what was surprising is that despite gloomy predictions that a track best known for motorcycle racing would lead to little overtaking, he climbed from 18th to second with a near-perfect recovery drive.

Swerving a struggling Aston at the start, Wittmann was into the top 10 in just four laps and ran sixth before pitting for an undercut strategy that helped put him into a net second position behind polesitter Rast, who reacted by pitting two laps later. Mike Rockenfeller's decision to run another two laps before stopping then proved crucial, as it paved the way for him to win for Audi Phoenix.

Muller, Wittmann and Eng have so far made sure Rast will not have it all his way in 2019, but the Audi driver remains one of the DTM's finest modern drivers

But, more importantly, Wittmann had come out on top against Rast. The DTM title favourite was forced to pit for a second time after failing to make the conventional one-stop strategy work - along with several other Audi and BMW drivers. But despite running in dirty air and battling his way through the field, Wittmann held on for second.

"All the people who know me, know I never give up and I fight until the end," he says. "The Norisring was definitely hard, especially with the technical issue which cost us 10 points in the [second] race, but that's how it is.

"Also [Sunday's] qualifying, it's frustrating, but at a certain point you have to switch to the other side and just go for the race and I think we managed really well. We fully focused on the racing. [We] did an awesome job in overtaking and as I said, we didn't expect it because that race track, that layout is a bit more towards difficult overtaking. [It's] difficult in tyre management and we somehow made it to overtake the guys in front and to make our way up to the front."

BMW wasn't convinced Wittmann could make the strategy work, even though he's one of the DTM's best in wheel-to-wheel battle and on tyre management. But his biggest challenge for a successful title bid is minimising the non-scores - a harder feat as the formula change has made reliability more of a factor in 2019.

And then there's Wittmann's other threat, which also gives BMW something to think about: the emergence of Philipp Eng. Now in his second DTM season, Eng has made a clear step forwards and was BMW's form driver until the most recent rounds, where Wittmann returned to the fore.

Eng's first DTM victory at Zolder owed much to a well-timed safety car, but the BMW driver has also taken a first pole position, three podiums and only failed to score twice.

Assen was a setback, as Eng felt he had not quite done his "homework" in finding the optimum set-up balance for qualifying and the race. But it was a glimpse into the mindset that is increasingly making him a contender, even if it's likely he will remain a dark horse.

When asked how he had changed as a driver for 2019, Eng says: "You have to have the experience [of a DTM car] so that obviously helps, I'm not doing anything different in particular. I just think the experience comes in and you deal differently with certain scenarios and situations."

But he then expanded on the methodical approach that's served him well, and it stems from his regular work as a driver coach, notably his work with Blancpain gentleman driver Karim Ojjeh.

"What helps me in that respect is that the days before I was a professional racing driver, I did a lot of coaching," Eng explains. "I saw a lot of data, onboard videos and there was always something to learn. I'm still coaching today. [Ojjeh] is obviously a gentleman driver but there is something to learn and that's how I approach the whole thing."

Muller, Wittmann and Eng have so far made sure Rast will not have it all his own way in 2019, but Rast remains one of the DTM's finest modern exponents.

With nine wins in his last 15 races, and his ability to maximise results on a bad day - such as his charge from the fringes of the top 10 into fifth after the enforced extra pitstop at Assen, or taking two podiums after start-line stalls this year - Rast has ensured his three rivals have their work cut out to defeat him.