MELBOURNE, Australia — Success-starved Williams, Toyota and Formula One newcomer Brawn signaled they could be ready for breakthrough wins by dominating practice Friday ahead of the season-opening Australian Grand Prix.

The presence of those three teams atop the time sheets will infuriate their rivals, some of whom are convinced their bodywork is illegal.

Williams, Toyota and Brawn showed an impressive pace Friday, aided by the additional downforce created by their rear diffusers which rival teams claim are too large and infringe new aerodynamics rules.

The three teams are racing under appeal this weekend, with other teams set to challenge the legality of their cars following next weekend's Malaysian Grand Prix.

Williams' Nico Rosberg was quickest in both the opening and second sessions Friday, posting a best of 1 minute, 26.053 seconds in the second.

Brawn's Rubens Barrichello was second fastest in the second session with 1:26.157, ahead of Toyota's Jarno Trulli on 1:26.350.

Trulli was among the drivers complaining of low tire grip in the cool conditions.

"I am still not completely happy with the car balance and, even though when you look at the timing sheets things look pretty good for us, the car isn't completely comfortable to drive," Trulli said.

Williams, seven-time winner of the drivers' championship and nine-time constructors' champion, has not won a race since the final event of the 2004 season at Brazil — a run of 72 races without victory.

Toyota is yet to win a race since entering F1 in 2002, while Brawn took over the former Honda team after the Japanese car maker pulled out following the 2008 season.

Australia's Mark Webber steered his Red Bull to a fourth-quickest time in the second session after a reliability issue in the opening stint.

Brawn's Jenson Button was sixth in session two, ahead of Toyota's Timo Glock, Williams' Kazuki Nakajima and Red Bull's Sebastien Vettel.

Button said there was more to come from his Brawn race car, and was not yet prepared to say that his team, Williams and Toyota would dominate Sunday's race and the early stage of the season due to their diffuser advantage.

"Ferrari are competitive as well," Button said. "Williams for sure have put in some quick lap times, and I don't know where that's come from.

"I still don't think we have been able to get the best out of the car," he said. "In a way its good that we are still not happy with the balance of the car."

Lewis Hamilton, last year's Australian GP winner and the reigning world champion, was 16th in the first session and 18th in the second, lending credence to his pre-race predictions that his McLaren team would struggle for competitiveness in Melbourne.

"We are not as quick as we would love to be, but we are working hard," Hamilton said. "We got through a program, and made some decent steps, so I'm happy with what we did today."

Ferrari's Felipe Massa and Kimi Raikkonen were 10th- and 11th-best in the second session.

"The pecking order that had established itself in recent years seems to have been overturned and we now find ourselves up against different and more numerous rivals," Ferrari team principal Stefano Domenicali said.

Friday's second practice session was the first chance for drivers to experience the twilight conditions, with Sunday's race to begin at 5 p.m. local time to fit in better with European television audiences.

Qualifying will also be at twilight on Saturday.