Jerez test - day one: 27 September.

Mark Webber topped the time-sheets as Williams kicked off the final big test of the Formula One season at a sunny Jerez circuit in Spain.

With the test running through to Friday, the BMW powered team was the only one to take to the track on Tuesday as preparations started for the final two races of the season in Japan and China.

Webber was by far the busiest of the three drivers in attendance, completing over 100 laps of tyre testing for Michelin, while Nico Rosberg - widely tipped as a possible team-mate for Webber for the 2006 season - also took part in tyre work before technical problems brought his day to a premature end.

Young gun Sebastian Vettel also got his first chance to test a Formula One car, completing 25 laps with a best time just under three and a half seconds off the pace set by Webber.

"On our first day at Jerez, the drivers managed to complete a substantial amount of mileage, in particular Mark, who recorded over 500kms while tyre testing for Michelin," test team manager Tim Newton said. "Nico was also on duty and covered 37 laps of tyre work before his half day session was ended prematurely by a technical problem. Nico is now on his way to Bahrain for the final round of the GP2 Championship. With a three point lead in the Drivers' rankings, the team would like to wish him all the best for a successful weekend.

"Sebastian Vettel made his F1 debut today as part of his BMW contract, awarded for winning last year's Formula BMW ADAC Championship. Sebastian performed well, completing 25 laps with no problems."

Testing continues tomorrow [Wed] when Toyota, BAR, Red Bull Racing and McLaren are all due to take to the track.

Leading performances (27 September) - Jerez:

Mark Webber Williams-BMW 1m 17.917s 125 lapsNico Rosberg Williams-BMW 1m 19.265s 37 lapsSebastian Vettel Williams-BMW 1m 21.364s 25 laps

All times unofficial - courtesy of Williams