Suzuka: Sebastian Vettel hit the barriers while Jenson Button, the only man standing between the Red Bull driver and a second Formula One title, led a McLaren one-two in first practice for Sunday`s Japanese Grand Prix.
Vettel, who needs only a point to be the sport`s youngest double champion at the age of 24, made a rare error on the exit to the Degner 1 curve.
He skimmed across the gravel and ended the 90 minute session as a sweaty spectator, removing his helmet and joining marshals behind the crash barriers with his car`s nose in the tyre wall.
The German, who can retain his title with four races to spare, was still third fastest in a hot morning session dominated by Button.
The Briton, who must win on Sunday and hope Vettel fails to score for the first time in 17 races dating back to last October, lapped the Honda-owned track in one minute 33.634 seconds.
Team mate Lewis Hamilton was second on the timesheets, 0.091 slower than the 2009 champion who regards Japan as a second home race and has just signed a new multi-year contract with McLaren.
Vettel lapped 0.456 slower than Button.
Australian Mark Webber, Vettel`s team mate who has still to win a race this year, was fifth behind Ferrari`s Fernando Alonso.
Vettel`s incident provided a talking point from the session but his pride was more dented than the car, which no more than nudged the tyre barrier.
Winner from pole at Suzuka for the past two years, the German has a 124-point lead over Button with only 125 still to be won.
Spaniard Jaime Alguersuari was a strong sixth for Toro Rosso, with Japan`s sole driver Kamui Kobayashi in 13th place for Sauber.
Indians Karun Chandhok and Narain Karthikeyan each took part in practice for Team Lotus and HRT respectively, with both having an eye on returning to racing at their country`s inaugural grand prix later this month.