Michael Schumacher's claim he is not in the running for victory on his comeback in Bahrain on Sunday appears to hold little water.

The seven-times Formula One champion and his team-mate at Brackley-based team Mercedes GP Nico Rosberg finished first and third at the end of Friday's two practice sessions ahead of Sunday's opening grand prix.

Sandwiched in between the duo was McLaren's Lewis Hamilton, his car now declared legal following scrutineering in relation to an aerodynamic device.

Appreciably, with a re-fuelling ban in place for this season, it has become increasingly difficult to assess lap times as you can never be sure as to a car's fuel load.

But with Rosberg at the top of the timesheets overall with a lap of one minute 55.409 seconds, and Schumacher less than half a second adrift of his fellow German, Mercedes are certainly in the running to take the chequered flag.

With reigning world champion Button fourth quickest, 0.667secs behind Rosberg, it meant that Mercedes-powered cars occupied the top four slots.

At the recently-lengthened track that sits in the middle of the Bahraini desert, stretched from 5.412km to 6.299km, last year's championship runner-up Sebastian Vettel pushed his Red Bull up to fifth, albeit a second down.

On his debut with the Grove-based Williams team, promising prospect Nico Hulkenberg made it four Germans in the top six, followed by Ferrari's Felipe Massa, whose team-mate Fernando Alonso was ninth, sandwiching an improved run from the Enstone-based Renault F1 team's Russian rookie Vitaly Petrov.

Sauber's pairing of Pedro de la Rosa and Kamui Kobayashi hauled themselves up to 10th and 11th with barely a tenth of a second separating them, albeit just under two seconds behind Rosberg.

Silverstone-based team Force India's Adrian Sutil, who led the way in the morning on a low-fuel run, ran heavy in the afternoon as he was 12th overall, 0.8secs slower than earlier in the day.