If Valentino Rossi is unfit to return to MotoGP action at Aragon later this month, several names have been mentioned as likely replacements.

Factory test rider Katsuyuki Nakasuga and Yamaha World Superbike's Alex Lowes, for example, both raced a YZR-M1 in MotoGP last season.

But according to paddock rumours at Misano, another rider in contention is their Suzuka winning team-mate Michael van der Mark.

Indeed, some sources have told Crash.net that the Dutchman - who rides alongside Lowes at the Yamaha WorldSBK team - is now first-in-line for what would be a MotoGP debut, if Rossi is absent from Aragon.

"We are considering all options and a final decision is expected to be taken on Monday next week," a Yamaha spokesman told Crash.net, when asked about van der Mark.

Rossi suffered displaced fractures of his right tibia and fibula during an enduro training accident on August 31, ruling him out of this weekend's home Misano round.

The nine-time world champion is determined to do all he can to return for Aragon, but admits that - at just 22 days since the accident - it is well short of the 40-day recovery forecast by doctors.

"Aragon would be three weeks after the accident. So it will be really difficult, but we'll try," Rossi told Italian TV on Thursday.

Although the stand-in rider should be confirmed next week, a decision on Rossi's fitness is unlikely to be made until the eve of the September 22-24 event.

Tech 3 boss Herve Poncharal has ruled out Johann Zarco standing in at the factory team.