New Lotus signing Kimi Raikkonen completed a headline-grabbing return to F1 action at Jerez by ending the first day of winter testing at the top of the timesheets.
The 2007 world champion, making a comeback to the sport this season after a two-year spell in the World Rally Championship, topped the 12-driver field with a best time around the twisty Spanish test circuit of 1:19.670 set mid-way through the morning's running, which was enough to edge out Force India's Paul di Resta by a tenth of a second.
Nico Rosberg was third in the 2011 Mercedes - the Brackley-based outfit opting to complete more work on their new car rather than press it into service for the first test - with Mark Webber fourth in the new Red Bull RB8.
The double World Champions' start to pre-season had been slightly delayed in the morning by the late arrival of some car parts following earlier heavy fog in the area. But once on track just before midday local time, Webber steadily worked his way down into the mid 1m20s by the end of the day having put 54 laps on the car everyone has to beat in 2012.
It was a relatively low-key start for Red Bull's two chief rivals, McLaren and Ferrari, who, for what it's worth given it was only the first day of pre-season, finished over one and a half seconds adrift of the pace set by Raikkonen.
Jenson Button, the 2011 championship runner-up, kicked off McLaren's programme in the MP4-27 - which uniquely continues not to feature the 'stepped' nose seen on all other 2012 cars launched so far. The Briton completed 62 laps to finish eighth on the times, one spot higher than Felipe Massa.
"It's been a good day: this morning, we ran through our installation and systems checks and the running was good," Button said. "We've been gathering data on aerodynamics, downforce levels, temperatures and the feeling inside the cockpit.
"We did a 15-lap timed run this afternoon, which is a good starting point for us - and the consistency was okay. It's been a positive day: there are no niggly areas with the car, which is nice. Overall, today was just a starting point, and was all about putting miles on the car. There are some promising signs, so I'm happy."
Ferrari said Massa, whose F2012 was initially painted with flow-vis paint across its rear wing for the team to complete some early aerodynamic evaluations, concentrated on - as is normal for the first test with a new car - data collection during the course of his 69 laps on track.
Meanwhile, Daniel Ricciardo was an encouraging fifth on the timesheets on his first day as a Toro Rosso race driver - although the Australian youngster had the unfortunate distinction of bringing out the first red flag of the year towards the end of the day's running.
The Red Bull junior team later confirmed that a loss of oil pressure triggered a default setting for the car's engine to shut down. Earlier in the day, the mandatory new higher exhaust position on the STR7 was thought to have been causing the car's rear wishbones to overheat.
Seven-time World Champion Michael Schumacher took over the W02 from Mercedes team-mate Nico Rosberg to get the ball rolling on the 19th season of his glittering career and ended up sixth, ahead of Sauber's Kamui Kobayashi who ground to a halt on the track late on to bring out the second red flag.
Up until that point Sauber had shown its C31 to be very reliable out of the box with their Japanese driver completing a sustained long run. He ended up with the most laps of anyone on the board, 106.
The rebranded Caterham team ended the first day 3.5s off the pace and had to cut short their programme after just 28 laps after damage to the car's starter shaft meant they were unable to start the engine.
Williams, who unveiled their new FW34 in the pit lane this morning, ran under Renault power for the first time since 1997 but they too encountered minor teething problems early on which restricted Pastor Maldonado to 25 laps.
HRT were the second team in action running a modified version of their old car as new signing Pedro de la Rosa made his debut for the Spanish outfit.
Provisional Tuesday times from Jerez
1) Raikkonen 1:19.670 75 laps
2) Di Resta 1:19.772 101
3) Rosberg 1:20.219 56
4) Webber 1:20.496 54
5) Ricciardo 1:20.694 57
6) Schumacher 1:20.794 42
7) Kobayashi 1:21.353 106
8) Button 1:21.350 62
9) Massa 1:22.815 69
10) Kovalainen 1:23.178 28
11) Maldonado 1:23.371 25
12) De la Rosa 1:23.676 44
