Former Sauber driver Pedro de la Rosa has been called up to replace Sergio Perez for the remainder of this weekend's Canadian GP.
On Wednesday, Perez was given the green light by the FIA to compete in Montreal following his massive shunt in Monaco qualifying.
However, the Mexican rookie admitted to his team after Friday's first practice that he was not feeling 100 percent.
"Of course I wanted to drive and I had no doubt I was alright," said Perez. "But apparently this is unfortunately not the case. I am deeply disappointed.
"I spoke to the team after the session and told them that I'm not a hundred per cent fit. I only want to drive when I'm a hundred per cent well. I need some more time to recover."
Sauber reportedly approached McLaren asking if they could run de la Rosa for the remainder of the weekend with the Woking team giving them the go-ahead.
Peter Sauber added: "This development hit us by surprise, because Sergio underwent thorough medical checks, first in the hospital in Monaco, then in a hospital in Zürich, and finally, the FIA doctors gave him the green light this Thursday in Montreal.
"Nobody could have foreseen that he would feel unwell. Maybe we are being overly cautious, but when it's about the health of our drivers we take zero risks.
"We want to thank Pedro de la Rosa and McLaren for helping us out in this situation."