William Haggas' six-year-old made the most of a drop in grade after being campaigned exclusively at the top level since his victory 12 months ago.
Runner-up in the Queen Anne Stakes at Royal Ascot last time, he was settled in midfield as Kaspersky cut out a steady pace.
Dane O'Neill got a beautiful split around the home turn as Kaspersky stole a few lengths but O'Neill exuded confidence and cut down his rival inside the final furlong.
Kaspersky held on for a deserved second with Hathal in third.
Click here for the full result and free video replay.
Haggas, speaking from Newmarket, said: "He looked to win all right. I was a bit worried about the ground as they had a bit of rain there, but he won well.
"The jockey seemed to be confident that he would catch Kaspersky up front.
"I would like to go to the Sussex (at Goodwood) with him, but I will talk to Sheikh Hamdan."
Mutakayyef was the second leg of a double on the card for Sheikh Hamdan and O'Neill, with the Owen Burrows-trained Laraaib (2/1 favourite) stretching his unbeaten record to three in the Playboy Club London Handicap.
The most valuable handicap of the afternoon, the totescoop6 Heritage Handicap, went to Mick Appleby's Danzeno.
The 4/1 favourite burned up the Ascot turf over the five furlongs, scoring by three-quarters of a length in the hands of Silvestre de Sousa.
Speaking from York, Appleby said: "That was brilliant. It was good to see him come back.
"He'll go for the Stewards' Cup at Goodwood now. Hopefully he can keep going."
Sky Bet cut Danzeno to 10/1 from 12/1 for the Qatar Stewards' Cup.
