Form guide: Mercedes under pressure in the heat

Could it really be that in just two weeks the massive advantage Mercedes had during the Australian Grand Prix weekend has been so rapidly eroded?

Friday practice at Sepang certainly suggested that the gap has closed, even if intuitively the 0.061s that covered pacesetter Nico Rosberg's Mercedes, Kimi Raikkonen's Ferrari and Sebastian Vettel's Red Bull-Renault at the end of the day seems too good to be true.

The four fastest cars over a single lap - Mercedes, Ferrari, Red Bull and Williams - all on their fresh-tyre run on the quicker, medium-compound Pirelli rubber, were covered by just two tenths of a second.

Fastest Friday times
1 Nico Rosberg      Mercedes          1m39.909s
2 Kimi Raikkonen    Ferrari           +0.035s
3 Sebastian Vettel  Red Bull-Renault  +0.061s
4 Lewis Hamilton    Mercedes          +0.142s
5 Fernando Alonso   Ferrari           +0.194s
6 Felipe Massa      Williams-Mercedes +0.203s

All of these laps were set on the first flying lap on medium rubber, except for Vettel. While some were struggling to keep their rubber alive for the full lap, the Red Bull driver was able to improve by around two tenths on his second attempt.

Potentially, Hamilton could have lapped faster as on his best lap he lost time in the second sector.

GARY ANDERSON: "Both Mercedes are right up there, which considering the team's performance in winter testing and in Melbourne is to be expected. But things seem a lot closer.

"The conditions here are very different and Rosberg is very closely followed on pure laptime by Raikkonen and Vettel, so you have the three engine manufacturers in the top three.

"The overall times so far are about three-and-a-half seconds slower than the comparable day last year, which is where you would expect things to be considering the loss in aerodynamics, the extra 50kg and perhaps a bit from the tyres.

"While you would assume Mercedes has something in its pocket, it is the three big-player teams up the front and you'd expect them all to be doing similar things on their fastest laps.

"After all, we've always known the Red Bull was a strong car aerodynamically so it's possible Renault has made another step."

LONG-RUN PACE

On Friday in Melbourne, the long-run performance figures gave a very accurate indication of how the competitive order on race pace stacked up. Here, though, things look more muddied, partly because we saw a wider range of approaches to the session.

Mercedes, for example, opted for two shorter long-run stints, first on the medium and then on the hard tyre with both Rosberg and Hamilton. Just as it was here last year, Mercedes is concerned about degradation.

"It's always challenging to get the compromise between qualifying and the race, especially this weekend," said Rosberg after the session. "With the tyres, we just have a lot more degradation than predicted. It's really tough to manage the tyres with less downforce and sliding more."

The temperatures certainly looked to be causing trouble for Mercedes, although the relative brevity of its runs, with both Hamilton and Rosberg doing eight meaningful laps on their medium stints, makes it a risky business to extrapolate tyre degradation with certainty.

Analysing the long runs, taking into consideration eight counting laps on mediums across the four leading teams, produces this ranking:

1 Mercedes  1m44.757s
2 Red Bull  1m44.920s +0.163s
3 Williams  1m45.549s +0.792s
4 Ferrari   1m45.584s +0.827s

The question here is what happens when the runs get longer. While some did run beyond eight 'counting' laps, it's difficult to be certain how the degradation will pan out from car to car. But what does seem to be clear is that Mercedes is very concerned about this.

What's more, the radio traffic during the session hinted that Rosberg was perhaps finding it possible to keep within the fuel-use limits, whereas Hamilton was having to be held back. But this is free practice, and the idea is to learn so there's no guarantee that pattern will hold come Sunday.

As for the rest, McLaren was disappointed with how today went. After taking a double podium in Australia, with Ron Dennis's bold predictions for a half-second improvement there was little sign of that here.

High temperatures also seemed to be making life difficult for McLaren, which looks more likely to be dicing with Force India than fellow Mercedes customer Williams and the Ferraris.

GARY ANDERSON: "On the longer runs, the Red Bull and Raikkonen in the Ferrari look fairly stable as far as tyres are concerned. On the Mercedes, the tyres look to be going away a bit earlier than the Red Bull or the Ferrari.

"It is down to how you abuse the tyres. When the lights go out and the race starts, that's your big decision. Today is about experiencing when they go off then reacting to that later in the weekend.

"You can't drive slowly and keep on forever because you will be too slow. It's all about how consistent you are and how you use the tyres. The key thing is getting the knowledge for Saturday and Sunday during Friday practice.

"McLaren looks to have dropped away and isn't as competitive as it was in Melbourne. But remember others had trouble there and Daniel Ricciardo finished ahead of the McLarens before being disqualified, and the Williams also should have beaten them, so perhaps this is more representative."

TYRES AND STRATEGY

The medium-compound Pirelli appeared to be the tyre of choice based on Friday practice, with the hard being slower but not appearing to offer any significant advantage in terms of degradation or wear.

"We saw between 0.9s and 1.2s difference between the two compounds," said Pirelli motorsport director Paul Hembery. "Degradation levels were actually pretty similar between the medium and hard, between 0.25s and 0.35s per lap, which is more than we anticipated. And the wear levels were also similar again."

But while two stops does appear to be potentially quicker, the increased degradation means that some might be forced into a three-stop strategy, so there could be a mix in approaches to Sunday's race.

GARY ANDERSON: "You might be biasing it towards three stops now. Coming into the weekend, a two-stop looked better than a three-stop, but not by much. If conditions remain as today, it could drift towards a three-stopper.

"The hard tyre could prove to be fairly durable, so you could maybe qualify on the mediums and then get onto the hard for a two-stopper. But there's not a massive difference in it and teams will have to see how things go at the beginning of the race.

"With the new regulations, I don't think anybody can go into a race absolutely certain of what they are going to do. It's too easy to create a plan and not deviate from it and let the situation go away from you. And with some rain on Friday afternoon after practice, that could clean the track up again and change the conditions."