Monterosso turned in an impressive display to land the King Edward VII Stakes for Mark Johnston and Frankie Dettori.
The 7-2 chance arrived having won four of his last five starts and was sent to the front halfway up the straight.
The result was never in doubt thereafter as the three-year-old excelled on this step up to a mile and half to pass the post two and a quarter lengths ahead.
Arctic Cosmos ran a fine race to finish second, with Buzzword filling the places.
Johnston said: ``That day at Ripon when he won a handicap was the day we really saw the class.
“He was in an impossible position. It was all credit to Royston (Ffrench) to keep him trying, but he won and we saw a good horse that day. It told us to start stepping up in class.
“You could see what a green horse we had then. He really didn’t know what his job was. He’s a completely different animal now.
“Frankie was full of confidence. He said to me he loved the horse and he had said after Newmarket that he really didn’t think trip was an issue that this horse had the speed for a mile but the aptitude for a mile and a half.
“We haven’t discussed future plans at all. Obviously the owners need to be consulted and we’ll talk to them.
“I did hear Frankie mention the Irish Derby to Sheikh Mohammed, so that’s maybe something to think about.”
Dettori added: ``I really like him and Jamie (Spencer) was very cunning at Newbury (on Green Moon). He was slow in front and kicked and caught me unawares.
“We stepped him up in distance, He keeps on improving and I thought it was a tremendous performance today and good credit to the stallion Dubawi. He’s done tremendously well this year.
“Perhaps a pop at the Irish Derby could be on the cards.
“He’s still learning and that’s a good sign.”
The runner-up's trainer John Gosden said: ``It was a huge run and I'm really delighted. We'll put him away now and bring him back for the St Leger.
“He could run in one of the trials or I could even look at a Listed race for him.”
Mahmood Al Zarooni, trainer of the third home Buzzword, added: “He’s run very well and Ahmed (Ajtebi) said he tried his best.
“He got a bump on the bend and without that he could maybe have been second.
“He’s had a lot of races in quick succession so he’ll have a break now and we’ll wait a while with him.”