A Plus Tard ran out a brilliant 22-length winner of the Betfair Chase under jockey Rachael Blackmore.
The 11-10 favourite, runner-up in the Cheltenham Gold Cup in March for trainer Henry de Bromhead, turned the Grade One contest into a one-horse race.
“It was a brilliant performance. He has loads of class,” said Blackmore.
Royale Pagaille was second with Chatham Street Lad and Clondaw Castle the only other finishers.
Bristol De Mai, seeking a fourth win in the race, could not reach the level of previous years and was pulled up, along with Waiting Patiently, while Imperial Aura fell.
It was another big triumph in a stellar 2021 for De Bromhead and Blackmore, who combined to win the Grand National with Minella Times in April.
Victory was also a boost for owners Cheveley Park Stud, after it was announced on Friday their leading sire Pivotal had died.
Lostintranslation (4-1) won the 1965 Chase at Ascot under Brendan Powell for the rejuvenated Colin Tizzard stable.
Evens favourite Buzz, trained by Nicky Henderson, took the Ascot Hurdle under Nico de Boinville.
Trainer Paul Nicholls was already thinking of next year’s King George VI Chase after 8-13 favourite Bravemansgame, ridden by Harry Cobden, landed the graduation chase at Haydock.
Isabel Williams, riding for her trainer father, landed the stayers’ handicap hurdle on 16-1 shot Dans Le Vent.