Fernando Alonso has dismissed Valentino Rossi's invitation to a three-round duel.
The MotoGP champion issued the challenge after Alonso said he was unimpressed by the Italian's pace in F1 tests for Ferrari.
"I think we should drive a Formula One car, a World Rally car and a MotoGP bike, add the times together and then we will see who is the fastest," Rossi said.
Alonso initially indicated he would accept the challenge, but the Spaniard has since made it clear he will not make the effort.
"I'm an F1 driver with a busy schedule, I've got no time to play around," Alonso said at Sepang. "He obviously has time on his hands.
"With all due respect to Valentino, I just said that he isn't among the five best F1 drivers and never will be.
"That's the end of it, I don't have anymore time to waste on it."