Lewis Hamilton topped both practice sessions in Austin on Friday as he prepared for the US Grand Prix with hopes of repeating his victory in 2012, the first time the race was staged here.
The Mercedes driver made it the 14th time in 17 race weekends he had come top in the second session but had to abort the final 18 minutes.
Hamilton complained about a strange shift coming across the finishing line, concerning fourth to fifth gear. His mechanics confirmed there was a problem and he was called into the pits.
He still beat his Mercedes team-mate and only championship rival, Nico Rosberg, by three thousandths of a second.
Ferrari’s Fernando Alonso was third, ahead of Red Bull’s Daniel Ricciardo, with Felipe Massa (Williams) and Kimi Raikkonen closing out the top six, though the Finn had difficulty finding the right set-up on his Ferrari.
Hamilton was also quickest in the morning run, ahead of Rosberg, after McLaren had dominated most of the session. Third-placed Jenson Button was less than a 10th of a second slower than Rosberg.
Button’s McLaren team-mate, Kevin Magnussen, who ended up fifth, was an early leader in the session, a 10th of a second behind the Toro Rosso of Daniil Kvyat, who eventually split the two McLarens. Alonso was sixth.
At the end of the first practice session the cars returned to the Circuit of the Americas track to enable the FIA to test a new yellow flag speed limit. This is expected to be introduced soon as the FIA works to improve safety procedures after Jules Bianchi’s accident at the Japanese Grand Prix. Bianchi remains in a critical but stable condition in hospital in Japan.
