The four times Formula One world champion was unmatchable as his red Ferrari blasted around the circuit in one minute 12.078 seconds in the first morning outing.

The German then pulled over at the pit lane exit with about eight minutes remaining of the second session after the car suffered a drop in oil pressure.

He stood on the pit wall, watching his rivals progress and waving to fans. Every other driver, except Finland's Kimi Raikkonen, managed more laps than Schumacher's total of 21.

Schumacher produced the fastest Formula One lap to date at Indianapolis, although that statistic meant little since the inaugural race on the new grand prix circuit was held only last season.

Finland's Mika Hakkinen, who celebrated his 33rd birthday on Friday with the fastest time of the day, was second quickest in his McLaren in 1:12.330.

The twice world champion crunched across a gravel trap after running wide at the start of the infield section of the circuit.

German Nick Heidfeld, in the Ferrari-powered Sauber, was third quickest ahead of the official qualifying session later in the day.

Michael's brother Ralf was fourth quickest, ahead of Brazilian Rubens Barrichello in the second Ferrari as teams fine-tuned their qualifying set-up.

Colombian Juan Pablo Montoya, who won the Indy 500 race last season and the last Formula One race in Italy, spun for the second day in succession but was still sixth fastest in his Williams.

Jaques Villeneuve, who also won the Indy 500 on his way to the CART title in 1995, struggled with his British American Racing throughout free practice and was 19th of the 22 drivers.

Tomas Enge of the Czech Republic, gearing up for only his second grand prix, was faster than the Canadian.

Ferrari also experimented with brake lights for the first time in Formula One. Teams have been given the option of whether or not to try them out in practice.

The vast grandstands on either side of the main straight at the historic oval circuit were fuller than previous days as fans took their seats ahead of the official qualifying later on Saturday.