Il Etait Temps was a shock winner as Facile Vega finished last of all in the Tattersalls Ireland Novice Hurdle at Leopardstown.
Both horses are trained by Willie Mullins, but it was Facile Vega who was widely expected to triumph as the 4-9 favourite.
He faded quickly out of it after turning for home, however, whereas his stablemate was able to accelerate under Danny Mullins to stun onlookers with a nine-and-a-half-length success at 14-1.
There had been drama earlier on, too, when one-time Derby favourite High Definition parted company with J J Slevin .
Mullins said: "They went a mad pace in front and it cost the favourite, I think.
We'll probably just have to ride him like a racehorse rather than a machine the next time
"Joseph's (O'Brien) horse (High Definition) wasn't able to jump at that pace and he paid the penalty.
"I was worried when I saw the pace going past the winning post first time, I said they can't keep this up.
"Then they jumped the two hurdles down the side and going around by the reservoir I turned to David Casey and said 'these two are going to break each other's heart'.
"High Definition lost his rider and I thought Paul (Townend) could get a breather into our fella but he didn't get a breather.
"That was what I was worried about here the last day, that he took off going to that hurdle and used himself up.
"We'll probably just have to ride him like a racehorse rather than a machine the next time because that's what Paul did today, he rode him like a machine rather than a racehorse.
"We'll change tactics on him the next day and hopefully he'll be back to what he is.
"Not taking away from the winner, he's a very good horse. He's just got to get his jumping right, he made a mistake at the first again today. He's a Grade One horse.
"I've always thought a lot of him, but he just has to get his jumping right. He got a very cute ride from Danny as well.
"He knew what was going to happen and he just popped him in behind and said 'I'll let the two in front have their battle and see if we can pick up the pieces afterwards' and he surely did.
"They just went too fast in front, the pace was wrong, and Danny had his fractions right."
Adding more on Facile Vega, Mullins said: "We'll go to Cheltenham. High Definition's jumping was always suspect and I think Paul didn't want him in front of him.
"You saw what happened with Lossiemouth yesterday and Paul just had that in the back of his mind going out today.
"All our horses are well entered up and Il Etait Temps will be in the Ballymore as well."
