Pascal Wehrlein has confirmed reports that he is back to full fitness after his early-season back injury.
The German had to miss the start of the 2017 season with fractured vertebrae, and he got another scare in Monaco when his helmet struck the barrier in a clash with Jenson Button.
Before he was cleared to race in Canada this week, he returned to the doctor.
"I made a check to ensure the old injury was not hurt again," Wehrlein is quoted as saying by Auto Motor und Sport.
"Of course I am very happy that I am 100% fit again. So I don't have to worry about that anymore."
Wehrlein has picked up four points for Sauber so far this season.