Godolphin colt Pinatubo has produced an astonishing performance to land the Vincent O'Brien National Stakes at the Curragh by nine lengths.

The Charlie Appleby-trained two-year-old was sent out the 1-3 favourite to maintain his unbeaten record at his fifth start on Sunday (Monday AEST).

Always travelling sweetly for William Buick, Pinatubo cruised to the front inside the three-furlong (600m) pole and when Buick let him loose with a furlong and a half to run, he simply rocketed clear.

"He's a trainer's dream once you get to know him, because he doesn't excite you in the morning to say the least," Appleby said.

"We started his career off at Wolverhampton for a reason, as we didn't really know he was in the yard.

"He's done nothing but improve with each run.

"He's the best horse I've ever had as a two-year-old, there's no doubt about it. He's exciting and it's great for the team.

"I gave him a gallop midweek with some of the nicer two-year-olds trying to give myself a bit of confidence and I probably did the reverse, as Royal Crusade (Champagne Stakes runner-up) put him in his place.

"He just goes through the motions and the jockey gets off and says he's moving well. He goes home and eats, drinks, sleeps and that's the end of it.

"We only ever see the best of him when he turns up at the track, which is a nice position to be in.

Appleby said the Dewhurst Stakes on October 12 was a likely target.

The colt is now as short as 4-5 to win next year's Guineas.

The news was not quite so good regarding the Appleby-trained Melbourne Cup winner Cross Counter who finished fourth, beaten four lengths, in the Irish St Leger won by the Dermot Weld-trained Search For A Song.

Cross Counter is scheduled to defend is Cup title in November.