Red Bull's Sebastian Vettel and McLaren's world champion Jenson Button shared the limelight in practice for an Italian Grand Prix both are desperate to win.
Button, shunted out of the previous Belgian Grand Prix by the German two weeks ago, went to the top of the timing screens in a sunny morning session at the super-fast Milanese circuit steeped in Formula One history.
Vettel, who has failed to convert his qualifying superiority into race wins, led the way in the afternoon in the former royal park where he took his first win with Toro Rosso in 2008.
The 23-year-old German, who will be chasing his eighth pole in 14 races, had been second fastest early on with a time just 0.097 slower than Button's best of one minute 23.693 seconds.
He lowered the time to 1:22.839 with a low fuel run later in practice, with Ferrari's Fernando Alonso and Felipe Massa second and third.
Button was fifth.
Championship leader Lewis Hamilton was fourth for McLaren.