Ralf Schumacher says he is close to agreeing to an extended contract with Williams but the deal is not done yet.

"I think you can assume that [the new contract will be signed]," the German Formula One driver told reporters at the IAA Frankfurt car show on Wednesday. "But it's not done yet. A few details still have to be sorted out."

Ralf's manager, Willi Weber, was earlier quoted as saying a new deal had been agreed.

"Everything is clear," Weber told the German weekly Sport Bild. "We will extend (Ralf's contract) to 2006."

Ralf, ruled out of last Sunday's Italian Grand Prix after a heavy crash in testing, said he assumed he would be fit again for the last two races and was amused by speculation about possible replacements.

"I'm doing everything to be really fit again and of course assume that I'll be in Indianapolis -- everything else is rubbish," he said on his website.

Schumacher, fourth overall, is out of the hunt for the title, but can still pick up points for himself and for Williams, who lead the constructors' championship.

Ralf's brother Michael, in a Ferrari, leads Williams' Colombian Juan Pablo Montoya by three points.

Doctors have advised Ralf to avoid stressful activity and he has a week of breathing and relaxation exercises ahead of him before the U.S. Grand Prix.

The German crashed in tests at Monza two weeks ago and suffered severe concussion. Spanish stand-in Marc Gene acquitted himself well in Sunday'a race, banking four points.

Formula One 2003 - Complete coverage