Barrichello fourth, but ready to race

The Brazilian helped slingshot Michael Schumacher to pole position and then shared the front row until he was demoted by the McLarens of David Coulthard and Mika Hakkinen.

His bid to regain the second starting slot was foiled by his Ferrari's lack of front end grip.

"On my last run, I decided to put on more downforce and get a tow from Michael," the Brazilian said. "However, I had a bit of understeer and I was not able to improve my time."

But Barrichello remains upbeat about his chances in America's first Grand Prix in nearly a decade.

"I am still confident because the performance levels of the top four cars are very similar," he insisted.

Barrichelo is determined not to repeat the bad start that saw him squander his front-row start at Monza. After a bad start he was eliminated in the first-lap pile-up.

"It's a shame not to be on the front row here as I was in Monza, but I made a terrible start there, so I hope to make a good one here," the Ferrari number two said.

"There is still some work to do to find the right compromise to suit both the slow and quick parts of the track.

"A lot will depend on the weather conditions."

Barrichello's main job in the race is to support Schumacher's bid to overhaul Hakkinen's two-point championship lead.

He is out of the running for the title, lying fourth in the standings with 49 points.