The 38-year-old Italian great was back on track in testing on Monday, 18 days after suffering a double fracture, and did another 20 laps on a road bike at Italy's Misano circuit on Tuesday.
He underwent a medical in Italy on Wednesday and decided that while his leg had not fully healed, the result was 'positive'.
"At the end I decided I will leave for Aragon and will try to ride my M1 this weekend," he said in a Yamaha statement.
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"If I will be declared fit to ride, I'll have the real answer after FP1 (first free practice on Friday), because riding the M1 will be a much bigger challenge. We'll see."
The Italian will have to pass a mandatory physical check by the chief medical officer at MotorLand Aragon, a circuit near Alcaniz in northern Spain, before he can participate.
Rossi, who missed the San Marino Grand Prix at Misano, is fourth in the championship, 42 points behind joint leaders Marc Marquez of Spain and Italy's Andrea Dovizioso with five races remaining.
"It remains to be seen if Valentino feels he can complete the entire race weekend, which is very demanding, especially at a circuit like MotorLand Aragon, with big elevation changes," said team director Massimo Meregalli.
"Should Vale feel that his injury is causing him too much discomfort, then Michael van der Mark will step in as the replacement rider."
Dutch Superbike rider Van der Mark, 24, has never ridden a MotoGP bike before.
He previously competed in seven 125cc (now Moto3) races in 2010 and the 2011 Dutch Moto2 round.
The Dutchman is also a three times winner of the Suzuka eight hours endurance race and has raced at the Spanish circuit seven times with World Superbikes and other support series.
(Reporting by Alan Baldwin, editing by Ken Ferris)
