- Associated Press - Friday, September 23, 2011

SINGAPORE (AP) - Formula One championship leader Sebastian Vettel set the fastest time in Friday’s practice sessions for the Singapore Grand Prix.

The Red Bull driver was two tenths of a second quicker than Ferrari’s Fernando Alonso in the second session. McLaren’s Lewis Hamilton third fastest ahead of Sunday’s race.

Ferrari’s Felipe Massa was fourth quickest around Marina Bay, with Red Bull’s Mark Webber fifth and Mercedes’ Michael Schumacher sixth.

McLaren driver Jenson Button’s practice session ended early after failing to negotiate a turn. He was forced to leave his car parked on the circuit.

Toro Rosso driver Sebastien Buemi collided with one of the concrete barriers along the tight street circuit, snapping the front right suspension.

Force India’s Adrian Sutil was seventh fastest while his teammate Paul di Resta had a brake and hydraulic problem that had his car being rebuilt for much of the session. The Sauber pair of Sergio Perez and Kamui Kobayashi were eighth and ninth, with Button in 10th.

The opening practice was delayed by half an hour _ and reduced to only an hour rather than the scheduled 90 minutes _ because of loose curbing.

The problem recurred late in the session when a bolt in the curbing came loose, prompting hasty repairs and a red flag. The curbing was removed at Turn 13 for the second session and was expected to be replaced before Saturday’s pre-qualifying practice.

Vettel leads the championship by 112 points and if he gets 13 points more than his closest rival Alonso on Sunday, he would have successfully defended his title with five races to spare.