MONTMELO, Spain (AP) Formula One had an incident-filled return to preseason testing on Thursday with champion Lewis Hamilton falling ill, German Pascal Wehrlein racing for two different teams, Williams' test driver Susie Wolff ending up in the gravel and a faulty seal ending Jenson Button's drive.
While others struggled, Pastor Maldonado of Lotus used a late flying lap to set the session's fastest time and edge Kimi Raikkonen after another strong ride for Ferrari.
Maldonado stopped twice in the morning because of sensor problems but later topped the timesheet on the first day of the second preseason testing with a lap in 1 minute, 25.011 seconds. That was still four seconds behind Raikkonen's benchmark time from the first preseason test two weeks before in Jerez. But both of the day's fastest drivers clocked quicker times than Hamilton's pole-setting lap from the 2014 Spanish Grand Prix on the same Barcelona-Catalunya Circuit.
Hamilton fell ill with fever after 11 laps and stopped driving early in the day. Wehrlein took over after Mercedes recalled him from Force India, where he had started the session.
''Today was a really good day in my career. I was quite surprised in the morning when I got the information that I would be driving the Mercedes in the afternoon,'' said Wehrlein. ''To drive two Formula One cars in one day was amazing.''
Both Hamilton and Wehrlein finished with two of the three slowest times of the day, with Hamilton at the bottom - over five seconds off Maldonado's pacesetting effort.
Ferrari, meanwhile, continued to impress with Raikkonen leading the charts through most of the session. In Jerez, the Finn and new teammate Sebastian Vettel had claimed the fastest time on three of the four test days.
McLaren's troubles mounted, however, when a faulty seal stopped Button after 21 laps. The team said the damage was sufficient to mean it will have to replace its power unit. McLaren, which has switched to Honda engines for this season, completed the fewest laps of any team in Jerez.
Honda said that the car needs a new component that won't arrive until Saturday, putting into doubt Fernando Alonso's turn at the wheel scheduled for Friday.
''We'll need to run a redesigned component to avoid a potential repeat of the problem,'' said Yasuhisa Arai, Honda's chief officer of motor sport. ''Unfortunately, we won't be in possession of that updated part until Saturday, which means that we may face the same problem when we run again tomorrow.''
Wolff was enjoying a promising start as Williams' test driver as she prepares for a possible opportunity to become the first female racer on the grid since 1976.
She was leading the field in laps completed before she and Felipe Nasr's Sauber ended up in the gravel off curve five. Williams said there had been ''contact'' between the cars, both of which were hauled off the track. Both returned in the final minutes, only for Nasr to again need assistance as the session ended under a red flag.
''I think Susie did not see me coming, and then we unfortunately collided in turn five,'' said Nasr. ''We had quite a lot of damage to fix. Despite the incident, it was a good day and I am positive about what I have seen today.''
Max Verstappen, the youngest driver in F1 history at 17 years old, got in much needed tracktime by recording a session-high 94 laps- eight more than Wolff- in his Toro Rosso.
''I completed almost a race distance,'' said Verstappen. ''I'm very pleased about managing that, as it's the first time I've done that many laps and it was a very useful experience.''
Testing continues through Sunday. Teams then take a pause before returning to the track for a final four days of testing next weekend. The season begins at the Australia GP on March 15.