Melbourne Cup-winning trainer Joseph O'Brien has pulled off another remarkable achievement with Edwulf winning the Irish Gold Cup at Leopardstown.

The nine-year-old collapsed in the closing stages of the JT McNamara National Hunt Chase at Cheltenham last March and his life was in the balance.

Edwulf happily returned to full fitness, but his comeback run, when pulled up at big odds in the Leopardstown Christmas Chase, hardly suggested he would be a player in the one of Irish National Hunt racing's biggest steeplechases on Sunday (Monday AEDT).

In what was a tremendous training performance, O'Brien somehow managed to coax him back to his best as he went on to land the Grade One race by a neck from Outlander in the hands of Derek O'Connor.

"He's always been a great horse," O'Brien said.

"It's a credit to everyone involved - the staff at home, the vets at Cheltenham last year and JP (McManus, owner) and Frank Berry (McManus' racing manager) who gave him all the time in the world.

"It's been a long road to get him back from where he was at Cheltenham when we thought he was gone.

"Derek is an unbelievable horseman. Horses just jump unbelievably well for him and he gets on great with this fella. We're over the moon.

"We'll see how he comes out of this first and we'll think about Cheltenham then.

"It's not too often you get a horse good enough to run in the Gold Cup so if he's well, I'd imagine he might go there."