Renault's Jarno Trulli has forced Formula One's three title contenders to take a back seat by seizing the top slot in first qualifying for Sunday's U.S. Grand Prix.

The Italian clocked the fastest Formula One qualifying lap yet at the Brickyard on Friday to remind Michael Schumacher, Juan Pablo Montoya and Kimi Raikkonen that Sunday's race would not be a private battle.

"It shows we are very competitive," said Trulli of his one minute 9.566 second performance.

"We've worked on improving the car toward the end of the season. As you can see, we are growing up."

Montoya, three points behind Schumacher with one race remaining after Indianapolis, kept the pressure piled on his rivals with the fifth fastest time in his Williams on a slippery track.

Ferrari's Schumacher was eighth and McLaren's Raikkonen, seven points off the lead, ninth with final qualifying to come on Saturday.

"I wasn't the quickest today, but I am in front of my main rivals and this is the most important thing," said Montoya, who braked too early into a couple of corners.

Schumacher said: "It was another qualifying session where rain in the morning had left the circuit pretty green and dirty so it was slippery for the first car going out.

"I am still eighth and that's not bad, it's a reasonable position really for tomorrow."

Raikkonen sounded relaxed as well. "I didn't do a very good lap and had a (bad) moment early on so I'm sure we will do better tomorrow," said the Finn.

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Montoya, aiming to become the first man to take the Indy 500 and U.S. Grand Prix at the same track, needs to win on Sunday to take the championship initiative into a final showdown in Suzuka.

Schumacher can claim a record sixth title at Indianapolis if he wins and the Colombian is sixth or lower and Raikkonen no higher than third.

His Brazilian team mate Rubens Barrichello, winner at Indianapolis last year, was second quickest for Ferrari on an overcast afternoon that turned to rain halfway through qualifying.

Australian Mark Webber was third for Jaguar ahead of Montoya's team mate Ralf Schumacher, returning after missing the Italian Grand Prix for medical reasons following a big testing crash.

"I believe we have the strongest package, no doubt about it and it's going to be a very tough race for Ferrari if they want to win," said Ralf.

The conditions were progressively faster for the first 10 cars before a downpour effectively ended the session as a competition.

"It was quite tough for everyone," said Webber. "The track was a bit more greasy than this morning's session...it's good to do a good solid lap and we'll see what the weather brings tomorrow."

Briton David Coulthard, Raikkonen's partner, made the most of the changing conditions to put some more distance between Montoya and Michael Schumacher with the sixth best time, ahead of Renault's Fernando Alonso in seventh place.

Canada's former champion Jacques Villeneuve was one of those who bore the brunt of the rain, the former Indy 500 winner finishing 16th in his BAR.