Lando Norris set a new record lap of the Monaco Grand Prix circuit to deny Ferrari's Charles Leclerc pole position for his home Formula 1 race.
Ferrari driver Leclerc had been a surprise but consistent pacesetter in every session prior to qualifying.
McLaren then looked a threat throughout the qualifying hour - Norris had shaded Leclerc by 0.011 seconds in Q2 - and a decision to try two runs at the end of Q3 ultimately paid dividends.
Norris shaded team-mate Oscar Piastri on the first of those attempts, but both were jumped by Leclerc as the chequered flag loomed - the Ferrari driver setting a 1m10.063s to take provisional pole.
But while Piastri - who earlier in Q2 had a big snap at hit the wall with his left-rear at La Rascasse - ended up third, Norris made his final lap count to take his second pole position of the season by 0.109s with a 1m09.954s.
Leclerc was fuming after being told he was second and lamented traffic on his first Q3 run, which he felt meant he lacked complete confidence on his final run, but still matched his best starting position of the season.
Behind Piastri, Lewis Hamilton recovered from a crash in final practice to set the fourth fastest time in the second Ferrari - although he was 0.428s from pole - with Max Verstappen an isolated fifth for Red Bull, 0.715s off after failing to improve on his final run.
Best of the rest
The absence of the other cars from F1's 'big four' in Q3 left sixth up for grabs for the midfield's standout, and Racing Bulls driver Isack Hadjar ultimately grabbed that - pipping the rejuvenated Fernando Alonso's Aston Martin to sixth by one thousandth of a second.
Esteban Ocon - who qualified and finished third in Monaco two years ago - was a strong eighth for Haas, with Liam Lawson making Q3 for the first time this season in ninth in the second Racing Bulls car.
Alex Albon looked a heavy favourite to grab that 'best of the rest spot' - he was third fastest in Q2 - but failed to improve on his final lap in Q3 and will start 10th for Williams.
Mercedes' disaster
Qualifying proved to be disastrous for Mercedes, with George Russell and Kimi Antonelli due to start the race from 14th and 15th.
Russell reported a loss of power up the hill through Beau Rivage as he began his first flying lap in Q2, cruising round thereafter before coming to a stop in the tunnel - which brought out the red flag.
He tried a restart procedure while he was stopped but Mercedes ultimately told him it was "game over, sorry mate", with Russell letting out an exasperated sigh over the team radio before he exited the cockpit.
Mercedes said that Russell "lost power after hitting a bump coming out of Turn 1 and was unable to restart the car after trying a number of switch change".
"It looks like a potential electrical problem at this stage."
Antonelli’s qualifying was already over by that point - despite making it through to Q2 - as he crashed at the Nouvelle chicane at the end of Q1.
He got too tight to the wall into the first part of the corner and clipped the barrier, breaking his front-left suspension as a result and ending up in the outside wall at the second part of the chicane.
He was flirting with an early exit anyway, having been 15th at that point and was not on course to improve his time.
The other Q2 exits
Even with the two Mercedes drivers out, improvements from the likes of Racing Bulls duo Lawson and Hadjar, Alonso - evidently pleased with his eighth-fastest time, exclaiming “I cannot do more mate!” - and Ocon meant more big names ended up being disappointed.
While Albon was a star once again for Williams, team-mate Carlos Sainz ended up a tenth off a Q3 spot in 11th. He did not improve on his final Q2 running, lamenting he had “no grip on this tyre”.
The second Red Bull of Yuki Tsunoda was unable to improve on his final lap - he never looked like doing so - and will start 12th, with Nico Hulkenberg 13th in the best of the Saubers.
Out in Q1
Hulkenberg set the first lap close to anything representative in Q1, a 1m13.354s, but more than two seconds had been taken off that initial benchmark come the end of the session (Leclerc setting a 1m11.229s on his eighth lap on a set of softs).
Gabriel Bortoleto had briefly snuck into the top 15 at the chequered flag but was soon bumped back into the drop zone by Hadjar, with the Sauber rookie ending up a mere 0.022s slower than Antonelli on the wrong side of the cut-off.
But Bortoleto did outqualify fellow rookie Ollie Bearman, who has a 10-place grid penalty for overtaking under red flags in FP2 and will start last, while Pierre Gasly qualified 18th in an Alpine that looked a marginal Q2 car at best prior to Q1.
Lance Stroll might well have dumped Antonelli out of qualifying had he not had to slow in sector two for the stricken Mercedes, though his own first sector had not been a personal best.
The Aston Martin driver's session was a hectic one.
If evidence was needed of the track evolution, the 1m12.878s that had Stroll top a third of the way through was the 19th-fastest time five minutes later. And by that point he'd also had a second serious impeding incident of the weekend - Stroll was given a one-place penalty for a substantial collision with Leclerc in FP1 - when Gasly had to jump on the brakes at the Nouvelle chicane.
Stroll did outqualify Franco Colapinto, but will start behind the second Alpine owing to his grid penalty.
Qualifying results
1 Lando Norris
2 Charles Leclerc
3 Oscar Piastri
4 Lewis Hamilton
5 Max Verstappen
6 Isack Hadjar
7 Fernando Alonso
8 Esteban Ocon
9 Liam Lawson
10 Alex Albon
11 Carlos Sainz
12 Yuki Tsunoda
13 Nico Hulkenberg
14 George Russell
15 Kimi Antonelli
16 Gabriel Bortoleto
17 Ollie Bearman
18 Pierre Gasly
19 Lance Stroll
20 Franco Colapinto
Provisional grid
1 Norris 2 Leclerc
3 Piastri 4 Hamilton
5 Verstappen 6 Hadjar
7 Alonso 8 Ocon
9 Lawson 10 Albon
11 Sainz 12 Tsunoda
13 Hulkenberg 14 Russell
15 Antonelli 16 Bortoleto
17 Gasly 18 Colapinto
19 Stroll 20 Bearman
