Following successive wins at Chantilly in September, the Andre Fabre-trained Kingman colt was the 6-5 favourite to complete his hat-trick and enhance his growing reputation in this Group Three contest.
Massam took the eight-strong field along for much of the one-mile journey before Magna Grecia’s two stablemates Circus Maximus and Western Australia moved to the front in an attempt to raise the pace.
Persian King and Magna Grecia followed them through before drawing clear to fight it out racing inside the final furlong.
Both juveniles gave their all, but with the rail to help, it was Persian King who claimed a neck victory in the hands of Pierre-Charles Boudot with the pair three lengths clear.
It was a performance that led to Guineas quotes of 14-1 (Paddy Power) but connections feel he will come into his own over longer trips next year.
Anthony Stroud, representing the winning owners, said: “He's a very good horse who has won his last three races.
“The jockey said he handled the ground really well but it turned out to be a tougher race than we thought. He certainly showed courage.
“He's out of a Dylan Thomas mare so we know he's going to stay further and I can see him going up in trip next season.
“He came here with Intello, ran in the same race as he did and I can see him following a similar path next year.”