Brazilian Rubens Barrichello pipped team mate Michael Schumacher to the top of the timesheets as Ferrari dominated Friday's first practice for the U.S. Grand Prix.
Barrichello lapped the 4.1-km Brickyard circuit in one minute 11.354 seconds, 0.265 quicker than the championship leader who is seeking his eighth win in nine races on Sunday.
The Brazilian won at Indianapolis two years ago and while yet to win this season is second in the championship, 16 points adrift of six times champion Schumacher.
The fastest time was well inside Kimi Raikkonen's 2003 pole position for McLaren of 1:11.670.
BAR test driver Anthony Davidson was the closest to the Ferraris, lapping 0.339 slower than Barrichello on a bright and humid morning in Indianapolis, with the Williams of Colombian Juan Pablo Montoya fourth.
Toyota's Brazilian test driver Ricardo Zonta was fifth while Jaguar's Swedish test driver Bjorn Wirdheim raised the struggling team's hopes with the sixth best time, ahead of BAR's Jenson Button.
The session was halted for four minutes to allow marshals to remove the stalled Minardi of Italian Gianmaria Bruni, who spun at turn eight.
