Ferrari's Michael Schumacher expects the Formula One world title to be decided by a last-race duel between himself and Colombian Juan Pablo Montoya.

The German, who could wrap up a record sixth championship in Indianapolis next week, told Italian newspaper Gazzetta dello Sport on Friday that he doubted the U.S. Grand Prix would settle anything.

"It would be nice but I think it is unlikely," he said.

The German leads Williams's Montoya by three points with only the Japanese Grand Prix remaining after Indianapolis.

Kimi Raikkonen is seven points off the pace and Schumacher played down his hopes, saying the 23-year-old Finn's chances of becoming the youngest champion depended on the top two hitting problems or his McLaren improving.

The German said he always knew Montoya, a former CART champion and Indy 500 winner, was a very competitive driver but believes Williams have made the difference.

"His car has been the surprise, it has been improved a lot. Now I think that the race for the title should be between the two of us," Schumacher said during a test session at the Jerez circuit in southern Spain.

"Raikkonen can only get into it if I or Montoya have problems or if his McLaren should improve its performance," he added.

McLaren have said they expect to be much stronger at Indianapolis and are targeting victory to keep Raikkonen in the title hunt.

Schumacher won the Italian Grand Prix last weekend in front of Ferrari's home crowd at Monza, ending a five-race losing streak with his first victory since Canada in June.

The German has said he expects his Ferrari to be competitive at Indianapolis and Japan's Suzuka circuit, where he has won for the past three years.

"I don't think there are any circuits where one driver starts as winner already," he said. "It depends on one's form on the day. The winner will be whoever manages to put the best package together. This time it could be us, I'm sure of it."