Jockey Johnny Murtagh sent the Aidan O'Brien-trained colt into the lead over two furlongs out.

He battled all the way to the line to hold off the challenge of Sagara with Zambezi Sun back in third.

The winner is now around a 5-1 chance, from 8-1, for the Prix de l'Arc de Triomphe at Longchamp on 7 October.

Murtagh said: "He'll improve for the race as he'd been off a long time.

"Once he got going I gave him a smack with my left hand and he was off.

"The pacemaker did his job and got me to the two-furlong marker and my fellow did the job in the style of a high-class horse.

"He's improved from Epsom and has now won an Irish Derby and a Prix Niel. He's got a great attitude and a great heart."

But Manduro's hopes of Arc success look to be at an end after the Andre Fabre-trained colt suffered an injury in the wake of his win in the Prix Foy at the same meeting.

The highest-rated horse in the world was winning over a mile and a half for the first time and was the second-favourite for next month's race.