Despite internet speculation to the contrary, Takuma Sato has ruled out a third driver role with Red Bull.

The Japanese driver tested for Toro Rosso in late 2008 and was highly impressive. Despite not driving an F1 car in anger since Super Aguri was forced to withdraw from the World Championship in April, after just four laps the Japanese driver was lapping quicker than Sebastien Bourdais, using the Frenchman's car and his engineers.

With Red Bull and Toro Rosso having confirmed their line-ups, there had been speculation that the highly popular Japanese driver might be handed the reserve driver role, but it is not to be.

"I am no longer in negotiation with the Toro Rosso or Red Bull teams about their third driver positions," Sato announced on his website this afternoon. "I am very disappointed that we were not able to come to an agreement with them but you never know what is around the corner.

"As everyone knows, I never give up so we are still looking for the best options for the future," he added.

Despite the obvious disappointment, should Mark Webber suffer any sort of recurring injury from his bike crash, or should Sebastien Buemi find it hard to establish himself, Sato would be as well to retain a friendly link with Red Bull, which no doubt explains the lack of bitterness or frustration in his comments.

Pitpass hears that the reserve driver role is most likely to go to New Zealander Brendon Hartley, though this is yet to be confirmed.