Sergio Perez completed qualifying at the Hungarian Grand Prix despite feeling dizzy and unwell, he revealed after winding up fourth on the grid.
The Racing Point driver said he was below his best as team-mate Lance Stroll outpaced him to take third spot in the duel between the two 'pink panther' drivers.
"I didn't feel 100 per cent physically during the qualifying," The Mexican said. "I was getting dizziness throughout the session and that's not great. I think I need to check with my physio to see what's going on, but I think I should be ok for tomorrow."
The controversial Racing Point team, whose 2020 car is under investigation after Renault officially protested its originality and validity, swept the second row of the grid.
"It's a great result for the team," said Perez. "We looked good all the way through so I am happy for that and I hope we can put it all together in the race and score a lot of points."
Perez's future with the team has been questioned this week following reports that four-time champion Sebastian Vettel, who is leaving Ferrari this year, is being lined up to replace him.
Stroll said: "The car was really strong all the way through -- we've had the pace and it was just about piecing it together during that qualifying session.
"So a great job from all the guys and now we are trying to grab some big points."
Sergio Perez said he felt dizzy and ill as he qualified in fourth for the Hungarian Grand Prix