Dalakhani recorded a famous success in the Prix de l'Arc de Triomphe Lucien Barriere at Longchamp today.
The Alain de Royer Dupre-trained colt had to dig very deep to fight off the brave challenge of Marcus Tregoning's Mubtaker.
Aidan O'Brien's High Chaparral finished well back in third for the second successive year, with Doyen fourth.
Christophe Soumillon raced towards the back of the field on the 9-4 second favourite in the early stages from his high draw.
High Chaparral (13-8 favourite), in contrast, was close to the pace being set by Dalakhani's pacemaker, Diyapour.
Mubtaker (25-1) was also handy and he was going very well in the false straight.
Dalakhani was also improving his position, though, and Soumillon never looked likely to panic on a horse he has always believed to be a superstar.
The winner's turn of foot brought him upsides Mubtaker and he then showed the necessary battling qualities to hold off a horse who had only been given the go-ahead to run an hour or so before the race because of ground worries.
Dalakhani won by three-quarters of a length, with High Chaparral, who just could not find any more in the straight, a further five lengths away in third.
Irish raider Vinnie Roe ran on stoutly to finish fifth. High Chaparral's stablemate Black Sam Bellamy was sixth.
"It's a race I wanted to win throughout my apprenticeship and it's unbelievable to ride a horse like him," Soumillon said. "He's a real champion and I love him so much."
Owner the Aga Khan, winning his third Arc, said: "He has got to be an outstanding horse, as a two-year-old, as a three-year-old and over all distances and all goings."