LONDON - Mark Webber showed Red Bull's pace as Formula One's final pre-season test kicked off in Barcelona on Tuesday, but McLaren also picked up speed after teething problems last month.

Redbull F1 driver Mark Webber of Australia walks by the paddock during a training session at Catalunya's racetrack in Montmelo, near Barcelona March 8, 2011. [Photo/Agencies]

Webber, who could become the first Australian to win his home race when the season starts in Melbourne on March 27, lapped a cold Circuit de Catalunya with a best time of one minute 22.544 seconds.

The time was set in the morning, on a qualifying-style single lap, before the team switched to longer stints in the afternoon.

"It was a pretty good day and not much has changed since last week," said Webber after completing 97 laps. "We got some good laps in today."

World champion Sebastian Vettel will be in the Red Bull on Wednesday.

McLaren's Jenson Button was second on the timesheets, 0.366 slower.

"The last couple of tests haven't been perfect for us, and I think that's partly due to us lacking set-up work," said the 2009 champion, who did 74 laps. "But today I think we made some positive progress with MP4-26's balance.

"I know there's not much testing left, I only have one more day in the car, but after today I feel we can make further positive progress over the next few days."

Button lapped with a bulbous 'porpoise' nose to the McLaren but the team said the eye-catching feature was purely for measuring purposes and would not be raced.

Russian Vitaly Petrov was third fastest for Lotus-backed Renault after taking over from German team mate Nick Heidfeld, who was suffering from a cold.

Heidfeld suspected champions Red Bull, who also have a Renault engine, still had plenty in reserve despite their obvious pace and was unhappy about his own team's lack of reliability.

"I think they (Red Bull) are still not showing everything," he told autosport.com.

"If you look at the sector times, they still have something in their pocket. So from the sector times at least, there might be even more that they are not showing.

"I still think that they are leading the pack at the moment. By how much? That is the question."