Daniel Ricciardo secured the first pole of his Formula One career with an incredible lap in qualifying for Sunday's Monaco Grand Prix.
Championship leader Nico Rosberg will join the Red Bull driver on the front row with his Mercedes team-mate Lewis Hamilton, who has not won at the principality since 2008, only third on the grid.
Ricciardo's emphatic lap marked the first pole position for Red Bull since the 2013 Brazilian Grand Prix.
Hamilton already trails Rosberg by 43 points, and the fraught defence of his championship crown took another dramatic twist after another engine failure prevented the Briton from posting a quick lap until the closing moments of qualifying.
Hamilton emerged for Q3 - the final phase of qualifying - but was told to stop at the end of the pit-lane with a fuel leak issue before his car was recovered by his Mercedes mechanics.
The 31-year-old was back on track with six of the 12-minute phase remaining, and in the closing moments he appeared on course to snatch a dramatic pole from Ricciardo, but a slow final sector means he will start not only behind Ricciardo, but his Mercedes team-mate, too.
With overtaking almost impossible at the narrow street circuit, Hamilton, three-tenths of a second slower than Ricciardo, cut a bleak figure in the post-qualifying press conference.
"It was a difficult qualifying, and I don't know what to say," Hamilton said. "The good thing was that I could get out and do a lap. I will do what I can tomorrow to salvage what I can from today's result.
"If the car keeps going I will be fighting as hard as I can with these guys. Hopefully it rains."
In contrast, Ricciardo, was thrilled to secure the maiden pole of his career.
"I knew coming into the weekend I had a shot at it," said Ricciardo who was fastest in practice on Thursday. "It looked good from Thursday. I think after the last few races, I feel like I have been driving well, but not getting maximum reward. I came in with a lot of confidence and a lot of belief."
Ricciardo's Red Bull team-mate Max Verstappen had thrilled the sport with his incredible victory at the Spanish Grand Prix to become Formula One's youngest-ever winner, but the 18-year-old crashed out of qualifying in dramatic fashion.
He will start last but one on Sunday after he clipped the barrier on the entrance to the chicane at the high-speed swimming pool complex, breaking his right-front suspension, and crashing head-on into the wall.
The session was immediately red-flagged as the debris from the accident littered the asphalt. Verstappen, who also crashed in final practice earlier on Saturday, emerged from the Red Bull cockpit with only his dignity bruised.
Jenson Button predicted the twisty street circuit would herald his best chance of a strong finish this season, but the 2009 world champion failed to reach the final phase of qualifying and will start only 13th. He was three tenths adrift of his McLaren team-mate Fernando Alonso, who made it through to Q3, and posted a lap good enough for 10th.
Elsewhere, Sebastian Vettel was fourth for Ferrari with Force India's Nico Hulkenberg fifth. Kimi Raikkonen qualified sixth, but will drop five places after being dealt a gearbox penalty.