With Harry Angel sent off favourite to follow up his scintillating Haydock win and Commonwealth Cup winner Caravaggio plus Quiet Reflection and The Tin Man all in the line-up, there was no hiding place.
However, they were all left in the wake of Dean Ivory's speedy grey, who survived a bump a furlong out to win impressively.
Adam Kirby adopted more patient tactics on Harry Angel, but he kicked clear with two furlongs to run. But despite coping with heavy ground at Haydock, Harry Angel was soon getting tired and the cavalry began charging.
Tasleet attacked on the far side, with Librisa Breeze in the middle of the track as Caravaggio also began to stay on.
Owned by Tony Bloom, who is the chairman of Brighton & Hove Albion and won the Cesarewiitch last week with Withhold, Librisa Breeze obliged at 10/1 under Robert Winston, beating Tasleet by a length and a quarter. Caravaggio was third.
Winston told ITV Racing: "It means a hell of a lot - my career was finished, only for this horse, and that's being honest. I was packing up last year, I gave my notice to Dean, but this horse and Mr Bloom have kept me going.
"Dean is a great man to ride for, he has great staff and brilliant owners, including Mr Bloom."
He added of the winner: "He'd get a mile plus, but has so much natural speed and is so genuine. I know I have been criticised a couple of times this year when he should have won, but that's the way you have to ride him.
"It doesn't really matter now, he's won the big one this year and this was the plan."
Ivory said: "I could not believe it. The ground and everything went right for us. He has been off a long time, seven weeks, and he has been so unlucky this year - we have got the luck when it mattered.
"That was the hardest field in the last 10 years and to come out and do it like that, I'm thrilled. We have had a bit of a rocky road. You persevere and hope for a bit of luck and it has come good today.
"He is a horse that has never had a clean run. This year is his year and I've seen him grow into a proper horse. Last year he was not a proper horse, but he is now.
"At one time I thought he had gone back a bit, but he got the gap this time. He is versatile and you can't say he isn't a six-furlong horse. You train him where the races are as really, he is a seven-furlong horse or miler.
"Robert Winston believes in the horse as much as we do. It has been a rocky road, but we have had this race in our mind for some months really."
William Haggas said of Tasleet: "He's run another great race and I'd say he just got outstayed this time.
"I very much hope he'll be back for next year, but that's to be discussed. If he is, he'll follow the same route as this year."
Harry Angel had to settle for fourth, and Clive Cox said of his July Cup and Sprint Cup victor: "It wasn't his day, but I still think he showed his usual zip and class when he went to the front here on much more testing ground than at Haydock.
"Great credit to the runners that finished in front of him, he was just coming to the end of his run.
"I don't think anyone has lost any confidence. We know on a different day, on better ground, he will be back.
"I will be looking forward to next year. I would say the first thing is to give him a nice winter break as it has been well earned."
