Mark Webber could have an important say in in the Brazilian Grand Prix after setting the pace in first practice.

The Australian is no longer in title contention after failing to score in the last five races, but his presence could prove vital to Red Bull Racing team-mate Sebastian Vettel, who could still catch championship leader Jenson Button.

The British star was only seventh fastest in the opening session.

German Vettel, 22, trails Button by 16 points with two grands prix remaining and ideally needs another victory to follow on from his triumph in Japan 12 days ago to keep him in the hunt.

With Button also fighting Brawn GP team-mate Rubens Barrichello, who is 14 points adrift, Webber could be in a position to come to Vettel's aid should the team ask for his assistance.

The 33-year-old was certainly on the pace throughout the entire 90-minute session around the undulating Interlagos circuit, closing out with a lap of one minute 12.463 seconds.

Webber finished 0.411secs quicker than Barrichello, with Vettel third quickest and Button seventh, the latter 0.678secs down.

Brawn GP chief Nick Fry declared himself happy with Button's work as the team focused on aerodynamics, notably to the front wing.

Brazilian Grand Prix Practice Gallery

The McLaren duo of Heikki Kovalainen and Lewis Hamilton suggested they will be in the mix this weekend as they were fourth and fifth in a session that was hit by two rain showers.

Both were just over half a second off Webber, with Williams' Kazuki Nakajima sixth, narrowly ahead of Button who set his best time of 1:13.141 with the last of his 29 laps.

Nico Rosberg in his Williams, Force India's Adrian Sutil and Kimi Raikkonen for Ferrari completed the top 10, followed by Toyota's Jarno Trulli and Nick Heidfeld in his BMW Sauber.

Sebastien Buemi was 13th for Toro Rosso, but ended up breaking his right-rear suspension in sliding into a tyre barrier at a time when the second shower had hit the circuit and the track was greasy.

Romain Grosjean propped up the standings, finishing 1.710secs down on Webber, and causing the only red flag 55 minutes into the run.

The Frenchman, unlikely to be retained by Renault for next season, ploughed into a polystyrene sign, sending white bits all over the track and forcing marshals into a five-minute clean-up operation.