Having landed the 10-furlong prize 12 months ago with subsequent St Leger winner Kew Gardens, the Ballydoyle maestro repeated the trick with the full brother to 2013 Derby hero Ruler Of The World.
Despite being a bit green the 7-2 shot found plenty for pressure under Seamie Heffernan to defeat I’ll Have Another by a length.
O’Brien said: “I’m delighted with him. That was a lovely experience for him. He stays well and the last day he won well and galloped to the line. He is a beautifully bred horse.
“It is possible (going to France for Criterium de Saint-Cloud). He is a lovely big horse and he doesn’t have to go there as he has had that experience coming here. It’s a possibility though as he is in it.
“He is a lovely horse as he is a brother to Ruler Of The World and half brother to Duke Of Marmalade.”