Fernando Alonso set a blistering pace on Friday morning at Barcelona to lead the timesheets with a 1:20.637, 0.336s up on his closest rival.
With blue skies overhead and just the occasional cloud, the second day at Barcelona kicked off with Michael Schumacher the first to set a lap time. However, the Mercedes GP driver was quickly overhauled by Pedro de la Rosa who in turn lost out to Fernando Alonso.
In three runs of five laps, Alonso succeeded in lowering the benchmark time to a 1:20.637, a comfortable 0.850s quicker than the week's previous best, which was set by Mark Webber on Thursday.
In fact, Alonso's average time of those laps, a 1:21.122, was, at that stage, even quicker than his nearest rival's best, a 1:21.571 set by Jaime Alguersuari.
An hour and a half into the session, Lewis Hamilton finally joined the party after an undisclosed problem kept him in the pits.
The McLaren driver almost immediately moved up to fourth place behind Pedro de la Rosa while Sebastian Vettel took fifth. The German, though, was concentrating on long heavy fuelled runs.
Tonio Liuzzi entered the fray, taking third place and then second, just 0.419s off the pace. But he wasn't the only driver on the move.
Vettel climbed ahead of Hamilton and then leapfrogged de la Rosa as he got within a second of Alonso's P1 time. The Red Bull racer's four-lap run saw him average a 1:22.367, which was also some way off Alonso's short-run average.
Schumacher, who completed just 14 laps in the first two hours, returned to the track but after three laps and only a minor improvement to his time was back in the pits.
"Some more changes to the car and Michael is now out doing a sequence of runs with some practice pit stop activity," Mercedes GP reported on Twitter.
The final hour before midday saw de la Rosa work on qualifying runs, improving to second place, 0.336s off the pace, while Schumacher moved ahead of Hamilton into sixth place.
And although Jarno Trulli continued lapping, he remained at the bottom of the timesheets. "Jarno not happy with the balance so will do some tests to investigate," revealed Lotus tech boss Mike Gascoyne.
Meanwhile, it was another wasted morning for Virgin Racing, who only ventured out two-and-a-half hours in the session. The team's VR01 had been damaged when Lucas di Grassi crashed on Thursday - and the knock-off effect was felt by his team-mate Timo Glock.
"Last of the new bits to repair yesterdays crash arrived from uk 1 hour ago," Virgin reported two hours into testing. "The guys are busy completing the car rebuild after a long night at the track and Timo will be hitting the asphalt very soon...
He wasn't.
It took a further hour before Glock finally ventured out, with Virgin reporting: "Installation lap OK on rebuilt car - a new start procedure outside the garage highlighted a small heat shield issue which is being fixed."
But it wasn't until an hour before lunch that the German actually set a time. He went on to complete 16 laps with a best of 1:26.622.
Unofficial Times
1. F. Alonso Ferrari F10 1:20.637 60 laps
2. P. de la Rosa Sauber C29 1:20.973 +0.336 46 laps
3. V. Liuzzi Force India VJM-03 1:21.056 +0.419 23 laps
4. S. Vettel Red Bull Racing RB6 1:21.258 +0.621 55 laps
5. J. Alguersuari Toro Rosso STR5 1:21.571 +0.934 24 laps
6. M. Schumacher Mercedes GP W01 1:21.689 +1.052 45 laps
7. L. Hamilton McLaren MP4-25 1:22.696 +2.059 21 laps
8. N. Hulkenberg Williams FW32 1:23.513 +2.876 80 laps
9. R. Kubica Renault R30 1:24.912 +4.275 23 laps
10. T. Glock Virgin Racing VR-01 1:26.622 +5.985 16 laps
11. J. Trulli Lotus F1 T127 1:26.677 +6.040 37 laps
Source: Planet-F1