Mercedes boss Toto Wolff says Lewis Hamilton may not be fit enough to race in Montreal next week due to the back pain suffered by the Mercedes driver in the Azerbaijan Grand Prix.
Hamilton was seen struggling to exit his car in parc fermé after Sunday's race in Baku, and then holding his back as he walked away.
The Briton later admitted he was biting down on his teeth, trying to hold on until the checkered flag and overcome his agony after 51 laps of bouncing, bottoming and battering onboard his car around Baku's track.
Wolff says Hamilton isn't the only driver physically struggling with the issue, but insists the seven-time world champion is one of the worst affected.
"He's really bad," said the Mercedes boss. "We have just got to find a solution.
"At this stage I think he is maybe the worst affected from all drivers. But pretty much everyone, as far as I understood from the drivers, said that something needs to happen."
When asked if Hamilton's physical torment may have put him at risk of not being able to race next weekend in Canada, Wolff said: "Yeah, definitely."
"I haven't seen him and I haven't spoken to him afterwards, but you can see this is not muscular anymore," he added.
"I mean, this goes properly into the spine and can have some consequences.
"I don't think this is only Lewis' issue. He's the one that is probably worst affected. But generally, it also affects George and many others.
"The solution could be to have someone on reserve, which we have anyway at every race, to make sure that our cars are running."
Mercedes' current reserve drivers are its pair of Formula E chargers, Stoffel Vandoorne and Nyck de Vries.