A Plus Tard finished with a flourish to collar Kemboy in the final strides in a vintage renewal of the Savills Chase at Leopardstown.
Kemboy looked sure to win the race for a second time in three years, having helped set a strong gallop in the early stages before stablemate Melon took over the lead with a mile to run.
Melon went well clear at one stage, but David Mullins did not panic on Kemboy and when Melon stuttered into the second last, Kemboy reclaimed the lead.
It looked sure to be a Willie Mullins-trained winner as at that stage Allaho was third, but as he dropped away, A Plus Tard could be seen making ground.
Stepping up to three miles for just the second time, Henry de Bromhead’s A Plus Tard (15-2) hit overdrive having jumped the last with many lengths still to find and he ended up providing jockey Darragh O’Keeffe with the biggest win of his career by half a length.
The race lost some of its lustre when the front two in the betting, Minella Indo and Delta Work, departed within two fences of each other early on the second circuit.
The winner was cut to 10-1 from 66s by Betfair for the Gold Cup at Cheltenham.
“He did everything right, he travelled and I thought we went a really good gallop,” said O’Keeffe.
“Rachael (Blackmore) said to me beforehand that she was going to sit upsides in front (on Minella Indo), and she was only a couple of lengths ahead of me, so I wasn’t worried.
“I sat away and had Paul Townend in front of me (on Allaho) and he (A Plus Tard) was pinging fences.
“When I gave him a squeeze after jumping the second last, he picked up and he galloped right to the line. After the back of the last I did (think I was going to get there).
“It was brilliant and I’m absolutely over the moon. I can’t thank Henry de Bromhead enough – it’s my first Grade One winner and my first winner for him. This lad had a real, live chance.
“There were a few questions about whether he stayed or not, but he definitely stayed anyway.”
De Bromhead hailed O’Keeffe’s effort, adding: “It was some finish, he was brilliant. He stayed really well and it was a super ride from Darragh.
“It was unfortunate with Minella Indo, but he seems OK which is the most important thing and Rachael seems OK.
“It’s very frustrating, but I’m delighted for A Plus Tard, for Darragh and for (owner) Cheveley Park (Stud).
“It was a brilliant ride from Darragh, he was very cool on him.
“I said it to (Cheveley Park managing director) Chris Richardson about Darragh and he was very happy after Rachael decided to go with Minella Indo.
“He’s an up-and-coming young rider and we were delighted to get him.
“He stayed on really well in the end. I thought he was staying on in the Ryanair last season and he definitely stayed on really well there.
“He won a Grade One here over two (miles and) one (furlong) last year and now he’s won over three miles. He’s still only six.
“We’ll see what we do now. He had a tough race there so I’ll speak to all the connections and decide after that. I’m delighted with today.”
When asked if he could be a Gold Cup contender, De Bromhead added: “Absolutely, he stayed at it really well and needed every inch of it.
“I wouldn’t like to make any plans yet. We’ll enjoy today as this is a pretty savage race to win.
“We’ll see whether it’s the Ryanair or the Gold Cup, it’s up to everyone involved.”