World champion Sebastian Vettel topped the times in opening free practice on Friday for the Indian Grand Prix, underlining his standing as the man to beat this weekend.
The 25-year-old German steered his Red Bull to a fastest lap of one minute 27.619 seconds in the 90-minute session at the Buddh International Circuit, three-tenths of a second ahead of nearest rival Jenson Button of McLaren.
Vettel, who snatched the lead in the drivers' standings two weeks ago in South Korea, delivered his best lap in the closing stages of a busy session during which Button's team-mate and compatriot Lewis Hamilton, who will switch teams to Mercedes next season, was fastest until the final minutes.
Two-time champion Spaniard Fernando Alonso of Ferrari, who is six points behind Vettel in this year's championship with four races remaining, was third fastest ahead of Hamilton and fifth-placed Australian Mark Webber in the second Red Bull.
German Nico Rosberg was sixth for Mercedes ahead of Brazilian Felipe Massa in the second Ferrari. The retirement-bound seven-time champion German Michael Schumacher, 43, was eighth in the second Mercedes.
Australian Daniel Ricciardo was ninth for Toro Rosso, ahead of Finn Kimi Raikkonen of Lotus.