Yamaha racing boss Lin Jarvis says the 2011 rider market will not start falling into place until it becomes clear whether Casey Stoner is joining Honda.
The 2007 world champion has been strongly linked to a switch from Ducati to Honda, where he would be reunited with former Ducati boss Livio Suppo.
Stoner, Valentino Rossi, Jorge Lorenzo and Dani Pedrosa are all out of contract at the end of 2010. An added complication is Rossi's declaration last year that he would not want to stay at Yamaha if Lorenzo was also retained as joint number one.
But Jarvis said it was Suppo's pursuit of Stoner for Honda that was key to the jigsaw falling into place.
"I'm still hoping we can keep both riders," Jarvis told Gazzetta dello Sport.
"We are on hold. Let's wait for Livio Suppo to make his moves and then we see what to do. When that happens, everything will move in a chain reaction."
Suppo told the Italian newspaper that he was optimistic of progress soon, and that a Pedrosa-Stoner line-up was possible, while current Honda rider Andrea Dovizioso was also still in contention.
"We hope that by Barcelona we can close the deal with Repsol, which looks interested," said Suppo.
"Obviously it's important there is a Spanish rider, and this is why we've started talking with Pedrosa, who wasn't too fussed about the possibility of having Stoner in the team.
"Let's also see whether Dovizioso carries on improving. Too many riders? Abundance problems are not bad."
Jarvis added that negotiations over Rossi's future were currently on hold following the Italian's injury.
"The truth is that we are talking to both riders in parallel, even though there's less of a chance of talking to Valentino now due to his absence," he said.
"When did we speak? Well, since the Mugello crash, there has been no contact. But at the moment the priority is his recovery.
"Obviously there are a few more questions now: what he wants to do, whether he comes back exactly as he was, whether the crash left some marks in his mind. Only he may know that."