MEXICO CITY: Charles Leclerc led a Ferrari one-two in a rain-affected final practice for the Mexican Grand Prix on Saturday with title outsider Valtteri Bottas best of the rest for Mercedes.
Lewis Hamilton, who can secure his sixth title at the Hermanos Rodriguez circuit with three races to spare on Sunday if he scores 14 points more than team mate Bottas, was fourth fastest on a drying track that started damp and slippery.
Leclerc's quickest lap of one minute 16.145 seconds was 0.027 faster than team mate Sebastian Vettel with Ferrari looking good for a sixth successive pole position in later qualifying.
Bottas was 0.114 off the pace, with Hamilton 0.236 slower than Leclerc - suggesting a tight battle for the top slot on the grid even if the fastest times came only at the end of the session.
"Leclerc and Vettel just a tenth ahead - we have a fight on our hands," Bottas was told over the radio.
Hamilton, who can become only the second driver after seven-times champion Michael Schumacher to win six titles, has clinched the title in Mexico for the past two seasons but looks likely to have to wait this time.
Nobody has won in Mexico since the race returned in 2015 without qualifying on the front row and Ferrari locked out the top two positions in Japan two weeks ago.
McLaren's Carlos Sainz was fifth fastest, ahead of Red Bull's Max Verstappen.
Verstappen is chasing his Mexican Grand Prix hat-trick after winning in 2017 and 2018 but has played down his chances of repeating the feat.
Thai team mate Alexander Albon was eighth after Red Bull replaced his chassis following a crash in second practice on Friday.
Pierre Gasly was seventh for Toro Rosso despite suffering from a stomach bug that has struck a number of people in the paddock.
Neither of the Renault drivers set a time with the team detecting problems with the cooling systems on the cars of Daniel Ricciardo and Nico Hulkenberg.
(Reporting by Alan Baldwin, editing by Clare Fallon)