Yeongam (South Korea): Jenson Button led team mate Lewis Hamilton in a McLaren one-two in final practice for the Korean Formula One Grand Prix on Saturday.
In a reversal of the top two places in Friday`s second practice, 2009 champion Button slotted in a quick lap of one minute 36.910 seconds right at the end of the session to oust the 2008 title winner from the top of the timing screens.
Button, winner in Japan last weekend, had started the morning with a new chassis after mechanics discovered damage to the previous one overnight.
He was 0.289 quicker than compatriot Hamilton, who looked more determined than ever after five races off the podium, after getting his timing right on super-soft tyres to secure a traffic-free lap.
Red Bull`s Australian Mark Webber, still chasing his first win of the season at a circuit that saw a double retirement for the team last year, was third fastest but 0.813 slower than Button.
Ferrari`s Fernando Alonso, winner of the inaugural Korean Grand Prix last year, was fourth with a new-look front wing on his car while Brazilian team mate Felipe Massa was fifth.
Red Bull`s Sebastian Vettel, who secured his second successive title at Suzuka on Sunday with four races to go and will be gunning for a 13th pole position in 16 races this season, was ninth and 2.7 seconds off the pace.
The 24-year-old German, frustrated repeatedly in trying to set a quick time, shook a clenched fist at Toro Rosso`s Spaniard Jaime Alguersuari after being held up behind him late in the session.
Red Bull have been on pole in every race this season and can wrap up the constructors` title in South Korea if McLaren, who are celebrating the team`s 700th grand prix, do not score more points than them.
With bright conditions but a drying track still damp from Friday`s heavy rain at the start of the hour-long session, Brazilian Bruno Senna spun and clipped his Renault`s front wing on the wall.