After Red Bull's Sebastian Vettel looked set to walk pole position in Singapore, it was Fernando Alonso who mastered the street circuit on Saturday night.
The Ferrari driver, having won from pole position two weeks ago in Italy, left Vettel and his team boss Christian Horner bemused by outpacing the fastest RB6 by half a tenth.
Vettel, 23, called his Q3 effort "messy", as Horner told British television BBC: "He touched the barrier on his final lap and that was the difference today."
In the sister Red Bull, championship leader Mark Webber qualified fifth, having not looked comfortable between the walls of the city layout so far this weekend.
The Australian, also behind the two McLarens for the start of Sunday's race, admitted he has had "trouble getting a rhythm around here".
"We underperformed," admitted Horner. "We should be two or three tenths up the road."
In contrast, it was a notably focused session for Alonso, who grappled with having to change some settings from the cockpit following teammate Felipe Massa's earlier gearbox failure.
"We made some safe changes in the car to avoid any risk," said the Spaniard, whose team initially believed Massa's problem was engine-related.
Alonso told his team on the radio: "No words, fantastic job today."
He will have a clear run to turn 1 on Sunday at 8pm local time, alongside fellow front row sitter Vettel.
"I think we had the car to be on pole but we have a very good car for tomorrow," insisted the German.
Ecclestone wants Singapore GP unchanged 'for 20 years'
Bernie Ecclestone says he would be happy if Singapore emulated the success of its night race with an unchanged format "for 20 years".
The F1 chief executive expressed his delight with the sold out event in the Asian city-state late on Friday at the opening of a Hublot watch boutique near the Marina Bay venue.
According to the local Straits Times newspaper, Ecclestone wants the Singapore race to stay the same until 2030 "and then see what needs to be changed".
The 79-year-old Briton said the race is a jewel in F1's crown and "keeps getting polished".
He did not mention two criticisms of the event.
After practice, having seen his friend Adrian Sutil's Force India launched spectacularly, Lewis Hamilton slammed the re-profiled turn 10 chicane as "ridiculous" and "the worst corner I've ever driven in formula one".
And reigning world champion Jenson Button pointed to track drainage as a problem, explaining that long after the rain had stopped, there was "a lot of water coming up through the circuit".
As has become the trend in Singapore this week, it has been raining once again on Saturday afternoon, prior to the evening practice session on qualifying day.
The F1 circus is generally very happy with the event, however, despite Nico Rosberg arriving back at his Pan Pacific hotel at 2pm on Friday night to find the kitchen had stopped serving dinner.
The German told AFP news agency: "The atmosphere is incredible and the concept of a night race works really well once you get into the routine of staying on European time."
Button admits Hamilton has been faster in 2010
McLaren newcomer and reigning world champion Jenson Button has admitted that he has not been as fast as his teammate Lewis Hamilton in 2010.
The 30-year-old, who has won two grands prix compared with Hamilton's three so far this season, said his countryman has been better at the wheel of an unbalanced car, and over a single qualifying lap.
"I need a car that is more stable than he does. In that respect Lewis is very strong," Button said in an interview with The Independent.
But the Briton insists he has not been destroyed this year by 25-year-old Hamilton, who was groomed by McLaren since he was a boy.
"Overall I think it's been very close with Lewis. But I am behind him, not in front. So qualifying is something that I still need to work on," Button acknowledged.
Some figures in the paddock believe that Button was effectively ousted by Brawn at the end of last year as the re-branded Mercedes GP wanted to pair the seven time world champion with the already-contracted Nico Rosberg.
But Button insists it was his "decision" to switch to McLaren, despite having had no input into the initial development of the MP4-25.
"I have made a lot of wrong decisions but I'm really happy with the one to move to McLaren," he said.