Practice 4: Schuey stays top

Up until now Schumacher has looked out of reach, but Button's 1m20.150s lap has given cause for excitement as qualifying looms. The Englishman appears at least to have the pace to challenge for his first pole position, and what had looked like a cakewalk earlier this morning for Schuey, may now turn out to be a hard afternoon's work.

Renault's Fernando Alonso was third fastest as he began to turn up the wick. The Spaniard dipped into the 1m20s bracket for the first time this weekend but still ended the session 0.7s off the pace. David Coulthard, whose session was interrupted by a harmless spin at the Variante Alta, was fourth after setting exactly the same 1m20.844s time as Alonso.

Williams driver Juan Pablo Montoya will not be happy to have been classified fifth, let alone over 0.8s slower than Button (the fastest of the Michelin runners). But at least the Colombian was quicker than Rubens Barrichello, the last driver in the 1m20s bracket, in the second Ferrari.

Takuma Sato was seventh ahead of Jarno Trulli and Kimi Raikkonen. Cristiano da Matta rounded out the top ten for Toyota.

Ralf Schumacher ended up a disappointing 11th fastest in the second Williams. The German would likely have been further up the list but for a trip across the grass at the Variante Alta, the kerbs of which have caught out quite a few this weekend.

Olivier Panis was 12th in the second Toyota ahead of Mark Webber's Jaguar and the Saubers of Giancarlo Fisichella and Felipe Massa. Christian Klien managed eight laps to finish the session 15th. This despite a heavy collision with the wall in his Jaguar during this morning's first practice.

Nick Heidfeld has moved back ahead of his Jordan team-mate Giorgio Pantano with a time that was over a second faster than the Italian could manage, while Minardi drivers Gianmaria Bruni and Zsolt Baumgartner brought up the rear.