The Charlie Hills-trained colt had finished second to each of the market principals on his last two starts of 2018, and went to the Classic without a previous run this season, having missed the 2000 Guineas at Newmarket after an unsatisfactory scope.
The race was billed as a race in two but Jamie Spencer had Phoenix Of Spain (16-1) smartly away and soon in a good position.
Too Darn Hot and Frankie Dettori loomed ominously in the centre of the course inside the final three furlongs (600m) out, as Magna Grecia weakened.
"It was very impressive. We were slightly concerned with the draw in one and were really conscious to get a good start," Hills said.
"To sustain that gallop all the way through and he just keeps lengthening. He's a big horse and whatever he did last year was a bonus. He's got a hell of a future ahead of him.
"He had some fantastic form last year when he was beaten by Too Darn Hot and Magna Grecia.
"We'll obviously enjoy today and then sit back down in a couple of days and prepare him for Ascot and the St James's Palace.
"After that we're really looking forward to stepping him up to a mile and a quarter. He has an Eclipse entry as well."
John Gosden was delighted with Too Darn Hot's performance following a delayed start to the season that meant he missed the Greenham and the Guineas at Newmarket.
"He ran a good race and I'm very happy with him," he said.
"It was a big ask coming back nine days after the Dante, but he ran a solid race.
"The St James's Palace is the target for him now."