With his contract due to expire at the end of the season, and having scored almost all of his team's Constructors' Championship points, there is growing speculation regarding the future of Nick Heidfeld.

Though Toyota is understood to be interested in signing the former F3000 Champion, unless the Japanese team makes remarkable progress in the months ahead, few would argue that it is BMW which offers him the best chance of race wins, and possibly a stab at the title. However, in addition to Robert Kubica, the German team has Sebastian Vettel waiting in the wings.

Asked why his team has not yet extended Heidfeld's contract, team boss Mario Theissen was giving little away.

"Both Nick and the team are currently delivering outstanding performances and are working really well together," he said. "So from that angle, there is no reason for either of us to be looking elsewhere for alternatives.

"At the same time, though, there's no rush to sort things out," he admitted. "We are speaking with Nick, of course, but we won't be giving any progress reports. We will make a decision before the end of the season and then announce that decision in due course."

Heidfeld is unlikely to want to wait much longer, and it remains to be seen whether he will take the initiative and begin negotiations elsewhere.