Frentzen

SILVERSTONE, England -- German Heinz-Harald Frentzen topped the testing times on his return to Sauber but ended the day in the medical center after crashing on his final lap of the session.

Frentzen, who will drive for the Swiss team in 2003, could replace out-of-favor Brazilian Felipe Massa at the United States Grand Prix at Indianapolis next weekend.

The German, who left Arrows earlier this year, was the fastest of the four drivers on the Silverstone circuit, before his crash at Stowe corner.

"Unfortunately, Heinz-Harald Frentzen went off into the tire barrier on his very last lap which caused considerable damage to the car," a team statement said. "He got out of the car himself and went to the medical center at the race track for a first check, which didn't reveal any signs of an injury at this point in time.

The statement said that an additional routine check would be done at an Oxford hospital later.

Frentzen had not originally planned to race again this season after Sauber said that he would physically not fit in this year's car, but Massa's collision with Jaguar's Pedro de la Rosa at the Italian Grand Prix led to the Brazilian being penalized 10 grid places if he races in Indianapolis.

Frentzen set a time of one minute 21.648 seconds with Italian Giancarlo Fisichella, of Jordan, second with a time of one minute 21.890 seconds.

"This was a very impressive comeback to the Sauber Petronas Team for Heinz-Harald Frentzen," Sauber boss Peter Sauber said. "He completed 71 laps and set the fastest time of the day, and he achieved this in a seating position which is only a compromise for him."

Briton Oliver Gavin continued to test for Renault after taking over from an ill Jenson Button on Wednesday. But he finished last behind the Renault of third-placed Spaniard Fernando Alonso.