Lewis Hamilton edged team-mate Nico Rosberg by the slenderest of margins to remain at the top of the timesheets at Austin’s Circuit of the Americas.

Hamilton had eclipsed his title rival team-mate by almost three tenths of a second in the opening practice session but in the afternoon Rosberg managed to close the gap to just three thousandths of a second. Third place in the session went to Ferrari’s Fernando Alonso.

It was Rosberg who went quickest in the opening part of the session on the medium tyre before the teams switched to the soft compound tyres with about 50 minutes to go. Rosberg again initially had the upper hand with Hamilton slotting into second place but with his second lap Hamilton stole into P1 by a tiny but significant margin.

With third-placed Fernando Alonso over a second down on Hamilton’s best lap, the Mercedes duo were in a class of their own in the session. They didn’t have it all their own way, however, though their chief adversaries were technical gremlins. Both complained of gear shift issues before Hamilton was told to make his way to the pits with a hydraulics problem.

After a tough morning session in which he was sidelined by an ERS issue after just five laps, Daniel Ricciardo bounced back in the afternoon to finish in fourth place with a lap of 1:40.390, some 1.3s down on Hamilton’s benchmark.

The Red Bull Racing driver’s team-mate, Sebastian Vettel meanwhile, was in trouble. With his team having already announced that he will start Sunday’s race from the pit lane due to a power unit change, Vettel encountered more problems with his team needing to change his car’s gearbox during FP2. He later took to the track for high fuel runs, which left him 18^th at the end of the session.

Behind Ricciardo, Kimi Raikkonen was sixth in the second Ferrari, with Toro Rosso’s Daniil Kvyat seventh and Kevin Magnussen eighth for McLaren.

The Dane’s team-mate Jenson Button, who had been third in the opening session, dropped to eighth place in the afternoon. In FP1 he had finished nine tenths adrift of P1 but in the afternoon the gap to Hamilton drifted out to 1.6s. The top ten order was completed by Nico Hulkenberg for Force India.

2014 United States Grand Prix – Free Practice 2 Result
1 Lewis Hamilton Mercedes 1:39.085 18
2 Nico Rosberg Mercedes 1:39.088 0.003 34
3 Fernando Alonso Ferrari 1:40.189 1.104 29
4 Daniel Ricciardo Red Bull Racing 1:40.390 1.305 30
5 Felipe Massa Williams 1:40.457 1.372 36
6 Kimi Räikkönen Ferrari 1:40.543 1.458 32
7 Daniil Kvyat Toro Rosso 1:40.631 1.546 34
8 Kevin Magnussen McLaren 1:40.641 1.556 38
9 Jenson Button McLaren 1:40.698 1.613 36
10 Nico Hulkenberg Force India 1:40.800 1.715 25
11 Valtteri Bottas Williams 1:40.828 1.743 37
12 Romain Grosjean Lotus 1:41.054 1.969 31
13 Jean-Eric Vergne Toro Rosso 1:41.110 2.025 36
14 Sergio Perez Force India 1:41.123 2.038 35
15 Pastor Maldonado Lotus 1:41.158 2.073 37
16 Adrian Sutil Sauber 1:41.332 2.247 33
17 Esteban Gutierrez Sauber 1:41.420 2.335 34
18 Sebastian Vettel Red Bull Racing 1:43.980 4.895