Valtteri Bottas topped the times ahead of his world championship-chasing Mercedes team-mate Lewis Hamilton in Friday morning's opening free practice for this weekend's Mexican Grand Prix.

Race Centre

The Finn, who headed the session for the first time since the British Grand Prix at Silverstone in July, clocked a best lap time of one minute and 17.824 seconds to outpace Hamilton by 0.466 seconds.

Hamilton's only remaining title rival, four-time champion Sebastian Vettel of Ferrari, was fifth fastest ahead of his team-mate Kimi Raikkonen, the pair separated from the Mercedes duo by the Red Bulls of Max Verstappen and Daniel Ricciardo.

READ: Hamilton flattered that rivals want to race with him

Local hero Mexican Sergio Perez was seventh for Force India ahead of Spaniard Fernando Alonso of McLaren, Brazilian Felipe Massa of Williams and Nico Hulkenberg of Renault.

ALSO READ: Verstappen sorry for Austin GP 'idiot' blast

The session was run in bright and dry conditions at the Autodromo Hermanos Rodriguez where an early interruption for a Virtual Safety Car (VSC) was followed later by a red flag when another Mexican Alfonso Celis crashed at the final corner in the second Force India an hour into the 90-minutes session.

Several other cars had spins or partial spins as the drivers adjusted to the unique conditions.

Hamilton will win his fourth world title on Sunday if he finishes fifth or better.