Lando Norris failed to complete his last lap in qualifying for Sunday's crucial Qatar Grand Prix to allow championship rival Oscar Piastri to take pole position.
Norris, who will start alongside his McLaren team-mate for the penultimate round of the campaign in Doha, held a slender advantage heading into the decisive concluding laps.
But the British driver made a mistake when he ran wide at the second corner, and was forced to abort, leaving Piastri the chance to usurp him at the top of the order.
Piastri, a winner of the earlier sprint race here, which took him to within 22 points of Norris' lead with 50 points still to play for, did not waste his opportunity, clinching pole by 0.108 seconds. Max Verstappen starts third to ensure he remains in the title hunt.
Norris will be crowned world champion on Sunday if he outscores Piastri by four points and Verstappen by one.
Norris was already showing signs of nerves when he saw three consecutive laps deleted in Q2 for running all four wheels of his McLaren over the white lines at turn 10.
That left him scrambling for a place in the final phase which he delivered in the nick of time, albeit two tenths slower than his team-mate.
He returned for Q3 and laid down an impressive marker to put him just 0.035secs clear of Piastri, with Verstappen four tenths back.
An anxious five-minute wait for Norris followed when the session was red-flagged when a streaky piece of plastic broke off Carlos Sainz's Williams.
Norris was the first of the championship contenders to take to the track, but his lap was over within the opening two corners after he ran wide and could not improve.
Piastri did to take top spot and Verstappen also bettered his opening run, albeit finishing nearly three tenths adrift of Piastri.
After he took third in the earlier sprint to extend his advantage over Verstappen to 25 points, Norris hit back at his rival's claim that he would have already easily wrapped up the title if he was driving for McLaren.
"Max generally has a good clue about a lot of things, but there is also a lot of things he doesn't have much of a clue about," said Norris in response to Verstappen's jibe.
"But it is also Red Bull's way of going about things, an aggressive nature and just talking nonsense a lot of the time. Maybe he would have done (won the title easily) but he hasn't done so far."
And it is Norris, despite missing the chance to take pole, who is just 24 hours away from dethroning the Dutchman without having to face a season-finale shootout in Abu Dhabi next weekend.
It was Groundhog Day for Hamilton after he suffered a hat-trick of Q1 eliminations.
Twentieth and last in Las Vegas a week ago, 18th for Saturday's sprint and 18th again for Sunday's main event.
These are desperate times for the seven-time world champion, whose first season at Ferrari continues to go from bad to worse.
Just as in qualifying for the sprint, Hamilton was close to four tenths off Charles Leclerc's pace in the other Ferrari and nine tenths off George Russell, who led the way in Q1.
Leclerc managed to haul his Ferrari into Q3 and he will start eight places ahead of Hamilton in 10th.
Leclerc has now out-qualified Hamilton at 18 of the 23 rounds. Hamilton will start with only Lance Stroll and Franco Colapinto and looks increasingly set to end his opening season in red without a single podium finish.
Final Positions after Qualifying:
1 Oscar Piastri (Aus) McLaren 1m 19.387s
2 Lando Norris (Gbr) McLaren 1:19.495
3 Max Verstappen (Ned) Red Bull 1:19.651
4 George Russell (Gbr) Mercedes GP 1:19.662
5 Kimi Antonelli (Ita) Mercedes GP 1:19.846
6 Isack Hadjar (Fra) RB 1:20.114
7 Carlos Sainz Jr (Spa) Williams 1:20.287
8 Fernando Alonso (Spa) Aston Martin 1:20.418
9 Pierre Gasly (Fra) Alpine 1:20.477
10 Charles Leclerc (Mon) Ferrari 1:20.561
11 Nico Hulkenberg (Ger) Kick Sauber 1:20.353
12 Liam Lawson (Nzl) RB 1:20.433
13 Oliver Bearman (Gbr) Haas F1 1:20.438
14 Gabriel Bortoleto (Bra) Kick Sauber 1:20.534
15 Alexander Albon (Tha) Williams 1:20.629
16 Yuki Tsunoda (Jpn) Red Bull 1:20.761
17 Esteban Ocon (Fra) Haas F1 1:20.864
18 Lewis Hamilton (Gbr) Ferrari 1:20.907
19 Lance Stroll (Can) Aston Martin 1:21.058
20 Franco Colapinto (Arg) Alpine 1:21.137
