Jerez De La Frontera, Spain: British former Formula One world champion Jenson Button made up for being unable to get out on the track on the first day of pre-season testing in the new McLaren MP4-29 by setting the fastest time on Wednesday.
Button's relief -- after he failed to make it out of the garage on Tuesday -- was in contrast to four-time world champion Sebastian Vettel, who endured further frustration with his new Red Bull.
Overnight rain meant that the test in wet conditions, originally scheduled for Friday, was brought forward and it was Button who made the early running.
The 2009 world champion then went even better in drier conditions in the afternoon to post a best time of 1min 24.165secs
Button had had to kick his heels on Tuesday as the newly modelled car, built to comply with a series of new technical regulations, failed to make it onto the track.
However, on the day McLaren announced that former Lotus team principal Eric Boullier would be joining as the team's new racing director, Button completed 43 laps to finish ahead of Ferrari's 2007 world champion Kimi Raikkonen in second, whilst Williams' Finnish driver Valtteri Botas was third.
Vettel's problems with the RB10 continued as having completed just three laps on Tuesday, the German managed only eight more, including just one flying lap, before having to retire for the afternoon due to an energy store issue in the Renault engine.
Moreover, it is unlikely that Vettel will get any more on track testing for the rest of the week with his new Red Bull teammate Daniel Ricciardo pencilled in to drive on Thursday and Friday.
Renault's engine problems weren't just affecting Red Bull as the Toro Rosso didn't make it out of the garage and Caterham rookie Marcus Ericsson managed just 11 laps before a technical issue also caused him to stop.
Mercedes built on their encouraging start before Lewis Hamilton's minor crash on Tuesday as Nico Rosberg racked up by far the largest number of laps with 97. The German finished fourth fastest on the day, just under one-and-a-half seconds behind Button.
Force India's Sergio Perez also suffered a disappointing end to the day after a positive start.
The Mexican -- who was dropped by McLaren after just one season at the end of last year -- had been running third fastest after completing 37 laps, but his afternoon was brought to an abrupt end when marshals had to extinguish a small fire at the back of his car before dragging it back to the garage.