Valtteri Bottas's participation in Sunday's Australian Grand Prix is in doubt after the Finn complained of back pain during qualifying in Melbourne.
The 25-year-old will start from sixth on the grid at Albert Park, but Williams's head of vehicle performance Rob Smedley has admitted that Bottas required further medical checks after limping out of the car.
He told reporters: "He felt pain under braking at the end of his second attempt in qualifying two, and then it kind of escalated from there through the third qualifying.
"I think he was in a great deal of pain then, but he still managed to be three-tenths [of a second] off the little group in front - the two Ferraris and Felipe - so he did a really good job.
"He was checked out at the medical centre and he has gone to hospital for further checks, and that's all we know at the moment. The update will be tomorrow."
Bottas's teammate Felipe Massa will start from third of the grid, behind the Mercedes duo of Lewis Hamilton and Nico Rosberg.
