Brazilian Rubens Barrichello led the way for Ferrari in free practice as the troubled champions geared up for Sunday's high stakes Italian Grand Prix.

Barrichello, who celebrated a Ferrari one-two win under very different circumstances at Monza last year when the titles were already won, lapped 0.151 quicker than team mate and championship leader Michael Schumacher.

Schumacher's main title rivals, Colombian Juan Pablo Montoya and Finland's Kimi Raikkonen, followed closely behind with Raikkonen third fastest and Montoya fourth and 0.555 slower than Barrichello.

With Schumacher on 72 points, Montoya on 71 and Raikkonen with 70 and two races left after Monza, Ferrari have to deliver to satisfy increasingly concerned critics after recent disappointments.

Williams are eight points ahead of them in the constructors' championship and Schumacher was lapped in the last race in Hungary before he trailed home eighth.

The German led for much of Friday's session, despite an early excursion across the gravel trap at turn 11.

Tyres came under particularly close scrutiny in the Monza pitlane on Friday, with Michelin introducing a new design of front tyres after two weeks of fierce argument over the legality of the previous ones.

Bridgestone tyre spotters were positioned in front of rivals' garages, a normal practice at races but more topical this time, logging data on clipboards.

Apart from Bridgestone-shod Ferrari leading the timesheets, Michelin teams filled seven of the top 10 slots suggesting the controversy would have less of an impact on their performance than feared.

McLaren's David Coulthard was fifth quickest ahead of Toyota's Brazilian Cristiano da Matta. Briton Jenson Button, seventh in a BAR, was the only non-Ferrari Bridgestone runner in the top half of the times.

Germany's Ralf Schumacher, an outside title contender 14 points behind his older brother Michael, returned for the first time after his major crash in testing at Monza last week to clock the ninth quickest time for Williams.

Hungarian Zsolt Baumgartner also returned for Jordan, replacing injured Briton Ralph Firman for the second race running. He was 19th of the 20 drivers.