The imposing son of Kingman looked a leaner specimen than when second on his comeback following injury at Chantilly three weeks ago and Pierre-Charles Boudot set out to give him a thorough workout, seizing the advantage from the off.
Halfway up the straight Persian King looked in danger of being overwhelmed by his attackers but knuckled down well to repel Pretreville.
The classy four-year-old is being aimed at a return to Group 1 company in the Prix d'Ispahan at Chantilly on July 19.
"I was pleased with what he did last time and satisfied that today he won in good style and moved very well," said Boudot. "I still had something up my sleeve. The others came at me early in the straight but he outstayed them.
"I don't think stepping up in trip would be a problem for him."
The Ispahan is over 1m1f and for this year only is open to three-year-olds, while Persian King's sole previous attempt at a mile and a quarter was in last season's Prix du Jockey Club, an inconclusive try given his subsequent health problems.