Lando Norris said an "unfair" yellow flag during qualifying ruined his entire Azerbaijan Grand Prix weekend and cost him crucial points in his title battle with Max Verstappen.
The McLaren driver recovered to fourth place from 15th on the grid in Baku, but was left ruing what could have been after his teammate Oscar Piastri won the race from second on the grid.
Norris was knocked out of the first session of qualifying when a yellow flag in the final sector forced him to abort a lap that would have comfortably seen him through to Q2.
The yellow flag was displayed because Esteban Ocon's Alpine, which was carrying damage from a collision with the wall earlier in the lap, was moving slowly through the high-speed chicane at Turns 18 and 19.
Typically, a white flag is shown for a slow-moving car, which does not require oncoming drivers to lift off the throttle, but marshals at the scene felt a yellow flag was more appropriate, forcing Norris to abort his lap.
"It wasn't fair," Norris said. "You don't have to be a scientist to work that out.
"It's not for me to decide, it's not for me to say. But it was unfair and for it to ruin my whole weekend ... I know I got a fourth today and that's not bad, but it could have been better.
"Oscar showed what was possible today. It was unfair. There was no yellow the whole lap and they put a yellow out just as I came past."
Norris said his qualifying lap would have comfortably secured him a place in Q2, even with a mistake at Turn 16 where he slid wide on the kerb.
"Did I go off the track just before it? Yes. Would I have still easily got into the top-15? Yes.
"I know there's a lot of people that thought it would have ruined my lap, but even with my off track, I only lost a couple of tenths and I still would have easily been in.
"People can say what they want and I find a lot of it funny but this was out of my control and it was something that was unfair."
Norris still managed to finish one position ahead of Verstappen and claim the fastest lap, thereby narrowing the gap in the drivers' standings to the Red Bull driver to 59 points with seven races remaining.
"It cost me a good amount of points in the championship today and kind of ruined my weekend," Norris added.
"So it's disappointing, especially because of how good the car was today. "I'm a guy that was thinking of what could have been, not how we did today necessarily. But I am very happy with today's performance."