Barrichello was in a class of his own at Indy on Friday

The Brazilian set the fastest lap in both sessions at Indianapolis, leaving the mark at one minute 10.365 seconds.

That was 0.602secs ahead of BAR test driver Anthony Davidson, with Williams' Juan Pablo Montoya third and Michael Schumacher fourth in the other Ferrari.

Jenson Button was fifth for BAR, with McLaren's David Coulthard failing to set a time in the second session.

The Scot had been just 18th fastest in the first session and then suffered an electrical failure on his first lap of the second hour.

Practice times in full

Button was 0.865secs off Barrichello's pace and just over 0.2secs behind team-mate Davidson.

Davidson is allowed to run because teams that finished outside the top four in last year's world championship are permitted to run a third car and driver in Friday's practice.

It was too optimistic and I told Sato that he is completely mad Felipe Massa

The Englishman has been able to use the situation as a means of signposting his talent in the hope of winning a race drive in 2005 with a series of impressive times.

BAR race driver Takuma Sato was less lucky. He collided with Sauber driver Felipe Massa 14 minutes into the second session.

The session was stopped for nine minutes while his car was cleared from the track and the Japanese was unable to take any further part in the day's running.

The drivers blamed each other for the incident.

Sato tried to pass Massa on the inside as they approached Turn One, but the Brazilian turned into the corner and the two collided.

Massa said: "I think it was too optimistic and I just told him that for me he is completely mad.

"I watched him in the mirror on the straight and he was far away from me. In the turn in, I watched him and he was not beside me.

Sato admitted his crash was an "unnecessary incident"

"When I turned in I watched in the mirrors and he just came and hit me, the back of my side."

Sato said: "He made a mistake in the last corner and so I caught him in the banking area and I was in the tow.

"I saw the blue flags waving and so going into Turn One I went to overtake him.

"But there was totally unnecessary movement and unfortunately we both touched. To me it is unbelievable.

"The stewards have not penalised us, and I agree it was a totally unnecessary situation in free practice because it is not racing. It was just unfortunate.

"As drivers, we obviously both have a different view of it, but I don't care."

Ralf Schumacher was sixth in the second Williams, with the Toyotas of Cristiano da Matta, Olivier Panis and test driver Ricardo Zonta and the McLaren of Kimi Raikkonen rounding off the top 10.

Jaguar driver Mark Webber, who is hoping for an improved performance from his struggling team this weekend, is 11th fastest.