The John Gosden-trained Gm Hopkins swooped fast and late to land the Royal Hunt Cup under an inspired Ryan Moore.
Moore buried the 8-1 shot in the middle of the pack before asking his mount to go about his business inside the final furlong.
Almost simultaneously Temptress was produced with her challenge on the far rail and the two thrust towards the line together, but Gm Hopkins passed the post a neck to the good.
Chil The Kite ran a fine race in third, with Balty Boys easily faring best of those that raced towards the stands side in fourth.
Spark Plug was still in with a place chance when dramatically stumbling and rolling over with half a furlong to run under Jimmy Fortune, but thankfully both horse and jockey got to their feet.
Moore said: "It was very wild where we were, there wasn't an awful lot of pace.
"My horse travelled very well but I had to go a little sooner than I would have liked, but Frankie (Dettori, on favourite Ayaar) was stopping in front of me.
"Luckily enough I was on the right side, but you can't do much about that."
Owner Robin Geffen said: "The horses have been brilliant but I have the best trainer in the world, there's no doubt about that.
"Today has been amazing, to come third in a Group One (Western Hymn) and then win the Royal Hunt Cup, I just hope we're still doing this in 25 years."
Gosden said: "We were worried the pace wasn't on our side, but it turned out it was.
"We got him covered up, but Ryan said he got there too soon as I told him to get there later.
"He was a bit unlucky at Newbury the other day, but he ran a super race and there's nothing like coming into these races in good form.
"He went up 6lb for that, but to win these big handicaps now you don't try to be clever with the weights as you just don't get into the race.
"It was a very high standard. Ryan rode a beautiful race and covered him up well.
"I think we'll go to France for a lovely Listed race and plan a lunch!"
