Seahenge was easy to back for the opening six-furlong maiden at Naas but went into plenty of notebooks after a snug victory.

Aidan O'Brien 's American-bred colt, who is a son of Scat Daddy and made $750,000 as a yearling, was making his debut with Donnacha O'Brien in the plate.

He raced in sixth of the nine runners, on the inner, as Pretty Boy Floyd took them along in a narrow lead. Yulong Warrior was nudged along on the outside to head Pretty Boy Floyd after halfway as Seahenge was soon pushed along in behind horses.

O'Brien went for the whip on Seahenge a furlong and a half down but the pair had a wall of four horses ahead of them.

Seahenge was then switched out at the furlong pole and rapidly devoured the ground to collar Yulong Warrior close him and win by a neck, without O'Brien having to get serious with him.

The winner drifted out to 6/1 from 10/3 in the morning and 9/2 at the track. The runner-up was a 5/2 chance. My Mystique the 5/4 favourite, was a further couple of lengths away in third.

Donnacha O'Brien said: "He's very green still and should improve when he's stepped up to seven furlongs or a mile. He just hung in behind horses a bit which was greenness more than anything but he did it nicely in the finish.

"He'll have to improve but he could be a Stakes horse."

Newcomer Kion from Michael O'Callaghan's yard, was the on-course gamble from 16/1 to 6/1.

However, he came in sixth but was short of room on the far rail in the final 100 yards when still in contention.

Additional reporting by Alan Magee