GREATER NOIDA (AFP) - Sebastian Vettel obliterated his own lap record as he topped both Indian Grand Prix free practice sessions on Friday, raising expectations he will snare his fourth world title this weekend.

The German, who has a massive 90-point lead over his nearest challenger Fernando Alonso, only needs to finish in the top five in his Red Bull on Sunday to make it four championships in a row.

He showed his intent by lapping at 1min 26.68sec in the first practice and improved that with 1:25.72 in the second, surpassing his own 2011 record of 1:27.24.

His team-mate Mark Webber, who quits Formula One at the end of the season, made it a one-two for Red Bull in both sessions. His best time of the day was 1:26.01.

The first 10 drivers all finished under Vettel's old lap record in the later session, promising a fast race on Sunday at the Buddh International Circuit on New Delhi's outskirts.

Romain Grosjean of Lotus was third quickest, ahead of Lewis Hamilton, Alonso, Nico Rosberg, Felipe Massa and Kimi Raikkonen.

The final practice will take place on Saturday morning, before the qualifying session later in the day.

Vettel, who has won the last five races this season, romped home easily in India in 2011 and last year and is strong favourite to triumph again on Sunday.

Anything higher than a sixth-place finish and Vettel will join compatriot Michael Schumacher and Juan Manuel Fangio of Argentina as only the third man to win four consecutive world titles.

The only way Vettel can be denied is if he fails to score a point in the remaining four races - provided Ferrari's Alonso wins at least three of them and finishes second in the other.