Sergio Perez on Thursday vowed to see how he feels after driving on Friday before committing to race this weekend on the streets of Valencia.
The Mexican rookie had expected to race two weeks ago in Canada following his Monaco qualifying crash, but pulled out after morning practice on Friday when he felt dizzy.
Perez, 21, had to pass medical exams in Montreal but at Valencia on Thursday he said the doctors are happy.
"They trust me and if I feel fine I will drive here," he told reporters.
Sauber, as well as McLaren reserve driver Pedro de la Rosa - who substituted for Perez in Canada - have confirmed that the same contingency plan is in effect for the European race.
"It (Friday) is an important day, especially the first practice to make sure everything is fine," said Perez. "I am quite positive everything will be okay."