As they have at several grands prix so far this season, McLaren set the benchmark for its rivals in the opening practice session at Barcelona's Circuit de Catalunya, with Lewis Hamilton and Jenson Button topping the timesheets.
Although Ferrari's Felipe Massa sat P1 early in the 90-minute session, it was the silver McLarens and the similarly-liveried Mercedes works car of Michael Schumacher who dominated as the chequered fell, with Hamilton enjoying a clear half-second advantage over his team-mate having clocked 1min 21.134secs around the familiar Spanish venue.
Button had been top of the times before Hamilton eased him aside, and then lost most of the final 20 minutes after running over a piece of discarded bodywork as he exited the pits. He remained confined to the garage as the McLaren engineers checked his MP4-25 for damage, and only returned to the track when it was too late to improve.
Schumacher, appearing more in tune with the revised Mercedes - which featured a new interpretation in the airbox area - was the closest opposition to McLaren, and the only other driver to lap in the 1min 21s. The German ended the session just 0.044secs adrift of Button, and ahead of Mercedes team-mate Nico Rosberg for only the fourth time this season.
Mark Webber and Sebastian Vettel rounded out the top five for Red Bull, the pair posting near-identical times as they pushed Rosberg back into sixth spot, just ahead of the closely-matched Robert Kubica, Fernando Alonso and Vitaly Petrov. Sauber's Kamui Kobayashi was only a tenth or so further back, but there was more frustration for team-mate Pedro de la Rosa, who was forced back into the pits before completing a timed lap and never returned.
Sebastien Buemi enjoyed an incident-free session, in contrast with his Shanghai outing, and took eleventh place from early pacesetter Massa, with Force India's Paul di Resta coming close to matching the Brazilian's best effort on the fourth of his Friday morning outings, this time in place of Adrian Sutil. Team-mate Tonio Liuzzi was a couple of places - and tenths - further back, with the second Toro Rosso of Jaime Alguersuari in between.
Joining Button and de la Rosa in losing time to a problem, Nico Hulkenberg came to a smoky halt towards the end of the session, but still wound up a place and a tenth shy of Williams team-mate Rubens Barrichello, who spent the morning chasing the handling of his FW32.
That left the Grove pair as the immediate target for the newcomer teams, headed in this session by Lotus duo Heikki Kovalainen and Jarno Trulli. The Norfolk-based team has made much of the improvement it hopes to make with its first raft of developments for the T127, and Kovalainen - despite spending the early part of the session in the garage with an engine glitch - a shade over four seconds off the pace.
The Lotus cars were followed, two-by-two, by Virgin and HRT, with Timo Glock and Lucas di Grassi comfortably clear of the returning Christian Klien and rookie Bruno Senna, who joined Rosberg, Vettel and Kovalainen in running out of road during the 90 minutes.