Austin, Texas: Formula One championship leader Lewis Hamilton posted the fastest times in Friday's two practice sessions at the U.S. Grand Prix, but abandoned the second session with about 10 minutes to go to deal with engine problems.
Hamilton's fastest lap at the Circuit of the Americas was 1 minute, 39.085 seconds in the afternoon. His Mercedes teammate and title rival Nico Rosberg was .003 seconds behind.
Hamilton is chasing his second world championship. He won the title in 2008 with McLaren and has a 17-point lead over Rosberg with 100 still available in the final three races.
The final race in Abu Dhabi will be worth double points, a new system that Hamilton this week questioned as an unfair way to wrap a season-long dual between himself and Rosberg.
