Barrichello, still searching for his first win of the year while the championship leader sets his sights on an eighth in nine starts, topped the timesheets in both sessions at The Brickyard.
The Brazilian's best lap, set in the afternoon, of one minute 10.365 seconds was more than a second inside Schumacher's 2003 race lap record of 1:11.473.
Briton Anthony Davidson, the BAR test driver who will not race on Sunday, was second fastest in 1:10.967 in another impressive performance at an unfamiliar track.
Colombian Juan Pablo Montoya, a winner of the Indianapolis 500 at the famous oval circuit that forms part of the grand prix layout, was third quickest in the second session for Williams ahead of six times champion Schumacher.
BAR's Briton Jenson Button was fifth quickest.
Barrichello has a good record at Indianapolis, winning controversially two years ago when race leader Schumacher slowed in the final straight to allow his team mate to close up and instead ended up second.
The Brazilian is second in the championship, 16 points adrift of six times champion Schumacher.
Both sessions were red-flagged, the second halted after BAR's Japanese driver Takuma Sato collided with Sauber's Brazilian Felipe Massa.
McLaren, suffering their worst season since team boss Ron Dennis took over in 1981, had another difficult afternoon with Briton David Coulthard pulling over early in the session and pushing his car clear.
