Oscar Piastri pipped McLaren team-mate and title rival Lando Norris to pole position for the potentially title-deciding Qatar Grand Prix.
The Australian beat Norris by 0.108 seconds after Norris, who had been fastest on their first runs by 0.035secs, aborted his final lap.
That gave Piastri the chance to put himself in a great position to win the race and take the title battle to a final-race decider in Abu Dhabi next weekend.
Red Bull’s Max Verstappen, the other title contender, will start third, also a threat to Norris. The Dutchman has to finish ahead of Norris to keep his chances alive.
Norris will become champion on Sunday if he wins the race, or beats Piastri and Verstappen, but he blinked first as the tensions rose in one of the most crucial qualifying sessions of the weekend.
Norris was blisteringly quick on his first lap but a loss of front grip in Turn Two on his second meant he had to abort and opened the door to his team-mate.
Piastri delivered with a superb lap to give himself the perfect opportunity to keep his title hopes alive.
Norris said: “I just got a bit of understeer and was going go off and had to abort. But it’s the way it is.
“Oscar did a good job and has been driving very well all weekend. Nothing to complain about, just didn’t do the lap. All to play for tomorrow.
Piastri said: “Everything felt great all weekend. The team did a great job, had a little bit of a question mark on which tyres I wanted to use.
“Did a lap on the used set and that threw a spanner in the works because didn’t expect them to be so good but went well on the new ones.
“Tonight we will review some things and see what I can do better than this morning, we are in a good position, progress, but it’s a long race.”
