Lewis Hamilton quickest but suffers P2 problems at US Grand Prix

Having been just under three tenths of a second quicker than Mercedes team-mate Nico Rosberg in P1, Hamilton shaded it by a mere 0.003 secs this time with a best lap of 1:39.085.

However, both drivers reported different gear change irregularities, with the Briton's car coming in 18 minutes early for some frantic investigation work in the pits.

Hamilton will take a 17-point lead in the drivers' championship into the third-last race of the season and is seeking a fifth straight victory following his triumph in Russia three weeks ago.

This was the 14th time Hamilton had topped the P2 timesheets from 17 attempts this year, but his technicians clearly have some work to do before Saturday's qualifying session.

Fernando Alonso was a distant third for Ferrari, finishing 1.104 seconds off the pace, while Red Bull's Daniel Ricciardo was fourth fastest, another two tenths of a second down.

Felipe Massa will take some heart from fifth place in his Williams, with Kimi Raikkonen next best in sixth for Ferrari, who appeared to struggle with their tyres.

Toro Rosso's Daniil Kvyat was seventh quickest, followed by the McLaren pair of Kevin Magnussen and Jenson Button.

Meanwhile, Sebastian Vettel will start Sunday's race from the pit lane after exceeding the number of engines permitted in a season.

With Marussia and Caterham not present in Austin, Texas, there are scheduled to be only 18 drivers competing.