Sir Michael Stoute’s charge was placed at that level last term, including at Royal Ascot, and following a narrow Listed success over Barney Roy on his seasonal bow at Ascot last month, punters were keen to get behind Ryan Moore’s mount.
Sent off the 11-8 favourite, Zaaki appeared to have plenty still to do at the top of the hill sitting a handful of lengths off the leading trio, with Bye Bye Hong Kong setting the pace.
However, when Moore gave the signal with a couple of furlongs to run, Zaaki started to extend himself and hit the front inside the extended mile distance.
Oh This Is Us tried to launch a last-gasp bid down the outside, but Zaaki had him covered and went on to triumph by a length.
Stoute told Racing TV: “It hasn’t harmed him, has it (gelding operation). He ran some very good races last year, but you have to say he has certainly progressed. He looks like a colt and is a powerful horse and physically he is in good shape.
“He has got mile-and-a-quarter form, so I didn’t think the trip would be a problem, I just felt he was having a little difficulty with the track.
“This looked like the next stepping stone and we got it right. With this fellow we will stop and think what we do. I’ve no fears of going back over a mile and a quarter.”
Moore said: "He is a horse that has got better this year. It probably wasn't his track, although they are saying it's a track record. He won nicely at Ascot, when he beat a very good horse, and was probably entitled to beat these today."
Richard Hannon said of Oh This Is Us: "He owes us absolutely nothing. He is my favourite horse. We've had one winner outside Europe and that is him. He is a lovely horse.
"He is perfect to take to Turkey later in the year. He is in Hunt Cup at Ascot. I think we will dot around the massive ones, he would win a Group Two. We could go to the Criterion Stakes at Newmarket and miss Ascot."
The William Jarvis-trained Chief Ironside was a further length and a quarter back in third.
Jarvis commented: "I am really delighted with him. He has got a big one in him.
"He just got caught out - that hill has caught him out in the last 100 yards. If it was a mile maybe he would have won, but there are no excuses. The winner is a good horse and progressive, a typical
Sir Michael Stoute horse.
"I think we will go for the Royal Hunt Cup (at Royal Ascot later this month) next."
Jockey Jason Watson added: "Chief Ironside ran a cracker. I think the hill just caught him out a little bit towards the end."