Kieren Fallon and Night of Thunder sprung a 40/1 shock in the QIPCO 2000 Guineas, flooring Kingman with a late thrust.
In victory, the successful colt was reversing Greenham Stakes form with the runner-up and also handing a first Classic success to Richard Hannon only months after taking over the licence from his father.
Kingman, sent off the 6/4 favourite, looked to have put a seal on the race when quickening clear at the furlong-pole.
But Night Of Thunder, who was one of six horses to race with Kingman in a group on the far side of the track, suddenly began to eat up the ground and despite hanging left across the width of the track as Fallon went into maximum drive, got up in the last couple of strides to score by half a length.
Fallon, claiming his first British Classic since Alexandrova's 2006 Oaks victory, said: "I thought he'd given it away, but he's a good horse and hopefully he can continue."
Six-times champion jockey Fallon was securing his fifth career success in the 2000 Guineas.
Night Of Thunder now has the option of travelling to the Curragh to contest the Irish equivalent on May 24, for which he would need to be supplemented.
"It's the stuff of dreams," said an emotional Hannon.
"I thought he'd run very well and we were a bit disappointed after Newbury. But all our horses generally need a trial and it's a tribute to him that he has come back and turned the form around with Kingman."
Hannon, who also saddled fourth-placed Shifting Power, went on: "It is a shame Dad couldn't be here but he left this morning for Goodwood.
"I think Dad's clever, I think he has a feeling when something is going to happen, he did it with me with Sky Lantern (last year's 1000 Guineas winner) as well.
"I can't say winning the Guineas was in the air, and we wouldn't have been too worried if it didn't happen, but they are three very good horses. But it makes a big difference to everyone at home and it's nice to have a 2000 Guineas winner.
"Toormore ran a little bit flat and Shifting Power ran a super race. We'll have a look at the French Derby for him.
"We'll have to talk to Bruce Raymond (racing manager for Night Of Thunder's owner Saeed Manana) but I'd imagine it will be either the Irish Guineas or the St James's Palace at Royal Ascot."
Kingman is also under consideration for the same two races.
Teddy Grimthorpe, racing manager for the colt's owner Khalid Abdullah, said: "He ran a great race. The field splitting was not ideal, but that's racing and we accept that.
"He has won his side of the field and we'll have bigger disappointments than finishing second in a Classic.
"The ground was fine and the winner's the winner, he won it fair and square.
"I imagine it will be the St James's Palace, although Ireland's not out of the question."
Australia, who raced in the stands' side group, kept on to finish third, just a head further back, in the process enhancing his Derby credentials. Bookmakers Sky Bet cut him from 9/4 to 7/4 for Epsom success.
"I was delighting with the run," said Australia's trainer Aidan O'Brien. "Obviously I'd have preferred for the field to stay together and we maybe had to get racing a little earlier than we would have liked to, but he ran a great race.
"Joseph (O'Brien, jockey) was always going to follow the pace, and with Toormore on his side it made sense to stay where he was
"He's still a baby. Obviously we'll talk to the boys but the Derby trip shouldn't be a problem. On pedigree, you'd say he was a Derby horse, but he was working like a Guineas horse."