Laurens made every yard of the running to inflict a dramatic defeat on Alpha Centauri in the Coolmore Fastnet Rock Matron Stakes at Leopardstown.
The Jessica Harrington-trained Alpha Centauri was sent off the 30/100 market leader as she went in search of her fifth Group One win on the bounce, but it was Karl Burke's Laurens who spoiled the party for the home favourite.
A multiple Group One winner herself, including in the French Oaks, Laurens stays well in excess of the mile trip and Daniel Tudhope - deputising for the injured PJ McDonald - was keen to capitalise on her guaranteed stamina and set out to make every yard of the running.
She was in control with two furlongs to run, but Alpha Centauri appeared to be just hitting top gear for Colm O'Donoghue down the outside, with Magical also trying to make her presence felt between the two.
However, Alpha Centauri appeared to momentarily falter as she went upsides Laurens, and the British raider took full advantage, going on to win at odds of 10/1.
Burke was thrilled with Laurens' victory and hailed the race as the best result of his career.
He said: "That was some performance and probably the highlight of my career so far. John (Dance, owner) was keen to come here and the reason we put her in was it was the only Group One fillies-only prep run leading into the Prix de l'Opera.
"After the Yorkshire Oaks, we were adamant that she didn't stay. We weren't going to complicate things so she made the running and made use of her long stride, which is her biggest asset. We didn't want to be dictated by any team tactics and we wanted to dictate to them.
"She has a huge engine and a huge stride, and we said we might kick a furlong earlier than they would expect us to.
"I would be very surprised if John doesn't want to go for the Sun Chariot now rather than the Opera. We would be keen to win another UK Group One if we can.
"John did say to me if we win one of these big Group Ones over a mile that she might stay in training, so I might hold him to that. If she does stay in training next year, she has a lot of options now over a mile and a mile and a quarter."
Harrington said of Alpha Centauri: "She got to the lead and she took a bad step. Whatever happened she took a bad step and then she took another one towards the end.
"She went there and whatever happened she did something, I saw it when I was watching it. She actually got to the front and I don't quite know what happened then.
"It'd hard to know (if she is sound) as the adrenaline is pumping now. Unfortunately that's racing and we'll live to fight another day."
Her rider Colm O'Donoghue said: "She did everything right. She quickened up and went half a length up, but then she lost her action and half-knuckled over for a stride or two.
"When she recovered she did it a second time. Fair do's to the winner, though, as she's a top-class filly in her own right as well."