SHANGHAI, China -- The performance advantage between Mercedes and Ferrari swung massively between Australia and Bahrain, but the early signs are that it might level out in China. Despite Ferrari's strong performance two weeks ago in Bahrain, reliability issues scuppered Charles Leclerc's first shot at a race win; and despite fixes being rolled out across the Ferraris and Ferrari-powered Haas cars in China, there are still signs that the car is fragile.
"I think it swings a little bit," Toto Wolff said of the competitive situation ahead of the third round of the season. "It was us in Melbourne overall: car, chassis and engine. In Bahrain it was chassis on our side, but the engine clearly on the Ferrari side and here from the first session you can see that the Italian horses work. So we need to find some performance, but on the chassis side it will be a tough fight between us."
Over a single lap, there was just 0.027s between the fastest Mercedes of Valtteri Bottas and the fastest Ferrari of Sebastian Vettel. Interestingly, they both had bad weekends relative to their teammates in Bahrain, but they already appear to have hit the ground running in Shanghai. Nevertheless, Vettel is convinced there are better things to come if he can get the car more to his liking ahead of qualifying.
"It's getting better but it's not 100 percent yet," he said. "If you feel that it's still stuck here and there, you can't be completely satisfied. But all in all, it was OK. At least we know where it is still stuck. It remains to be seen whether we will find it."
Meanwhile, the stars of Bahrain, Charles Leclerc and Lewis Hamilton, both made mistakes on their hot laps that left them 0.8s and 0.7s off their respective teammates. Leclerc lost most of his time in the final sector when he had to back completely off the throttle when running wide in the final corner. It was only a minor misjudgement and the rest of the lap looked fairly clean, but getting out of the throttle on the drag to the finish line was costly and he paid the price by finishing the session seventh-fastest.
Hamilton's problems cost him less time to the top two, but look more concerning. Throughout the lap, he was struggling with understeer -- when the car does not react to the driver's steering inputs -- delaying him getting on the throttle out of turn three and nine, while also causing him to miss the apex by over a metre at turn 14. It looks like an inherent setup problem with the car and one that he will be working hard to dial out overnight.
"I would say the car in general is not that easy to drive," Hamilton said. "But we are going to work on it tonight to find some tweaks and see what we can do tomorrow. This track has gone from being my strongest track to not being a strong circuit at all, so I have got a lot of work to do. But obviously the car has got the pace in it to compete at the front, so I just have to figure it out."
As was the case in Bahrain, Ferrari still has a clear advantage over Mercedes on the straights. In a back-to-back comparison with similar corner-exit speeds from turn 13, Vettel was clocked 12km/h faster than Hamilton at the end of the kilometre-long back straight. The overall power advantage amounts to a lap-time advantage of 0.3s from that straight alone, underlining the collective power of those extra Italian horses Wolff referenced.
But given the impressive cornering performance shown by Bottas, the extra pace Vettel thinks is in the Ferrari, Hamilton's propensity to bounce back from a poor Friday and the relative unknown of Leclerc, the battle for pole should still be interesting.
Amid fears of more reliability problems, Ferrari were forced to end Leclerc's session early and to allow the mechanics to strip down the car's cooling system. If Ferrari has an obvious weakness right now, it is reliability, and the precautionary measures on Friday meant Leclerc missed out on his usual race simulation at the end of second practice.
Reliability is becoming a touchy subject at Ferrari following Leclerc's problem in Bahrain. The issue, which cost Leclerc the race win two weeks ago, was traced to a short circuit in the control unit for one of the engine's fuel injectors and has required the team to roll back an upgrade to its control electronics.
"Reliability is a big challenge," team principal Mattia Binotto acknowledged on Friday even before the cooling issue on Leclerc's car emerged. "We know that reliability is key and we need to be perfect on that and it didn't happen in Bahrain.
"The problem we had was a problem we understood and was isolated to a unit. What we did here in China is revert to an old specification, a specification we know pretty well and we have good statistics in terms of quality and hopefully that will be sufficient."
Reliability aside, it is not yet clear whether Ferrari will hold the same pace advantage it had in Bahrain this Sunday. On the soft tyre -- on which the top-running teams are likely to start the race before switching to the hard -- Mercedes had a clear advantage. Over like-for-like lap counts on the soft compound (and with anomalous slow laps removed from the data), Bottas averaged lap times 0.3s faster than Vettel.
A comparison with Hamilton's long runs isn't really fair as he started on the medium tyre when on the heaviest fuel load and then moved to softs as his fuel load came down. For the record, his average on the softs was a further 0.8s faster than Bottas', but the vast majority if not all of that gap was down to fuel load.
Bottas and Vettel went on to do similar runs on the hard tyres at the end of the session, but, underlining how tight it is at the front, Vettel had the edge by 0.6s on the harder compound. Part of that is likely down to fuel, as Bottas switched to the hards earlier than Vettel, but it still seems odd that Mercedes should have an advantage on the softs and a large deficit on the hards. However, the two compounds require different approaches to car setup, and it's possible Mercedes has started the weekend at one end of the setup spectrum and Ferrari is at the other.
"The biggest problem here in Shanghai, because of the characteristics of the circuit, is that if you use the hard compound or soft compound, you need a car that is behaving in a different way," Pirelli's head of racing Mario Isola explained. "With the soft compound, you have to protect the rear tyres because you need a lot of traction in some corners. With the hard compound, you cool down the tyre a lot on the long straight, especially if it is cold, and then you suffer understeer and that is causing more wear on the front. If that starts the graining, you also have degradation on the front.
"With the hard compound, you should protect more the front than the rear because it is a lot more consistent on the rear tyre and you are not degrading the rear tyre like you are with the soft under traction. So you have these two different behaviours and ideally you would set the car up in a slightly different way for each compound. Obviously you have to find the compromise and they will decide their race strategy according to all this."
With the knowledge gained from Friday practice, both Mercedes and Ferrari are likely to work toward a compromise solution that works across both compounds. That means the gaps in performance on the two compounds may not be so extreme by Sunday, but even if they exist to some it extent, it should still make for a thrilling race if Mercedes is quicker on one tyre and Ferrari on the other.
The Red Bull in the hands of Max Verstappen appears to have made a step forward this weekend. On a single lap, he was 0.15s off Vettel, and on the long runs on the soft, he was 0.2s off. Considering Red Bull won this race a year ago, it's worth keeping an eye on his progress in FP3.
Pierre Gasly continues to struggle in the second Red Bull, but he put his lack of pace down to a day spent testing new parts.
Renault also looks more competitive this weekend. The team has yet to fulfill its potential this year but seems to have a genuine pace advantage over Haas on both one-lap and race runs.
Another midfield team to look out for is Toro Rosso. The single-lap pace wasn't spectacular, but the long-run pace using the hard compound tyre was not far off those of the top teams. Soft tyre pace appeared to be sacrificed as a result (see Isola's quote above for an explanation), but this could be the weekend we see the underlying pace of the Toro Rosso come to the fore.