Whirl gained Epsom compensation when edging out Kalpana in an enthralling Paddy Power Pretty Polly Stakes.

Ryan Moore was quickly away dictating terms aboard the 13-8 second-favourite, with Colin Keane never far away aboard the Juddmonte-owned Kalpana and must have thought the race was his for the taking when Whirl was asked for maximum effort with two furlongs to run with Kalpana still travelling menacingly.

However, Whirl was not for giving in and after a titanic tussle the Wootton Bassett filly pulled out extra inside the final furlong to shade a length and a quarter verdict and deny Juddmonte back-to-back victories in the feature event after Bluestocking 12 months ago.

“She’s an incredible filly. She’s just progressed and she loves getting into a fight,” said O’Brien.

“Obviously we saw that she stays a mile and a half at Epsom. She’s absolutely concrete, really. We knew that obviously she wouldn’t mind the mile and a quarter as she was very impressive in York when she won the Musidora.

“They got into a battle turning in and battling all the way up the straight like that at the Curragh takes some courage and they kept going together. Ryan said he felt 50 yards from the line that she had a look at the camera and he knew he had her then.”

O’Brien was winning the Pretty Polly for the sixth time and reserved special praise for Moore, who was joining the list of great jockeys who have won the race three times.

“Ryan gave her a brilliant ride, he got the fractions absolutely spot on,” added O’Brien.

“It’s a difficult thing when you are running a mile-and-a-half filly back at a mile and a quarter. You are trying to spread the stamina out over a mile and a quarter without stretching the elastic too long, but he got it absolutely spot on.

“He got the favourite to challenge him and this filly gets a mile and a half so there was no point turning it into a sprint. It was the plan to spread it out and let the two of them get together and see who was going to be the best.

“As they say ‘let the best horse jump the ditch’ after that. Two great jockeys, what can I say about Ryan, day in day out he’s incredible.

“They went strong and the two of them went together. Ryan and Colin knew they were each other’s dangers and they weren’t going to give each other an inch, which they couldn’t afford to.

“Those kind of races are few and far between. When you have that type of quality horse lining up and two riders like that. On ground like this, in a place like this, it’s a very special weekend.”

As for the future for his winner, O’Brien is inclined to keep an open mind, with Whirl’s Epsom conqueror Minnie Hauk also up his sleeve for the season’s major events.

He said: “She can go anywhere now this filly. She can come back here to the Oaks, she can go to the Nassau (at Goodwood).

“She’s an unusual filly. She’s tough and she’s not even blowing there, her nostrils weren’t even flaring.

“She’s obviously a very high-class filly and it’s very exciting. It’s possible she’s kept apart from Minnie Hauk, but the lads could let them run together in the Oaks.

“I’d imagine if Minnie Hauk comes back to the Oaks and she’s well she’ll be let go by herself and this filly could do other things.

“She’s not slow either.”