Stradivarius suffered his first defeat in almost two years as Aidan O'Brien's Kew Gardens came on top in a pulsating climax to the Qipco British Champions Long Distance Cup.
The remarkable Stradivarius has completely dominated the staying division over the past couple of seasons - with back-to-back wins in the Yorkshire Cup, Gold Cup, Goodwood Cup and Lonsdale Cup seeing him scoop the Weatherbys Hamilton Stayers' Million in both 2018 and 2019.
Having added the Doncaster Cup to his glittering CV last month, John Gosden's popular chestnut was the 8-13 market leader to stretch his unbeaten run to 11 - a streak which goes all the way back to him finishing third behind Order Of St George in this race two years ago.
Everything appeared to be going according to plan for the market leader for much of the two-mile journey, with Frankie Dettori seemingly content to bide his time as Withhold and Kew Gardens' stablemate Capri forced the pace.
Kew Gardens - winner of the Queen's Vase at Royal Ascot, the Grand Prix de Paris and the St Leger at Doncaster last season and runner-up spot in the Ormonde Stakes, the Coronation Cup and the Irish Leger so far this term - was the 7-2 second-favourite in the hands of the trainer's son, Donnacha, and travelled strongly to the lead soon after the turn for home.
Dettori swiftly went in pursuit and Stradivarius looked set to emerge triumphant after ranging alongside and even poking his head in front racing inside the final furlong.
However, Kew Gardens refused to yield and after a thrilling duel, the pair passed the post almost as one before the judged confirmed the Ballydoyle inmate the winner by a nose.
Gosden's second string Royal Line was five lengths away in third.
King Of Change ran out an authoritative winner of the Queen Elizabeth II Stakes.
Runner-up to the reopposing Magna Grecia when a 66-1 shot for the 2000 Guineas at Newmarket in early May, Richard Hannon's charge had made just one competitive appearance since - making a successful return from over four months off the track in a Listed event at Sandown.
Ridden confidently by Sean Levey, the 12-1 chance travelled strongly in midfield before quickening smartly to grab the lead with over a furlong still to run - and never looked in serious danger of being caught.
French raider The Revenant - bidding for a seventh straight win - did his best to close the gap late on, but King Of Change was ultimately well on top and passed the post a length and a quarter to the good.
Safe Voyage ran a big race to be best of the rest in third, ahead of the front-running Veracious.
Magna Grecia and the well-backed favourite Benbatl both toiled in the testing conditions and finished well beaten.
Star Catcher rounded off her excellent campaign with victory in the Qipco British Champions Fillies & Mares Stakes at Ascot.
John Gosden's filly was a maiden at the start of the season, having finished sixth on her only juvenile start at Chelmsford.
However, a good case can now be made for her being the best middle-distance filly of her generation after adding this Group One prize to her earlier big-race wins this season in the Ribblesdale at Royal Ascot, the Irish Oaks at the Curragh and the Prix Vermeille in Paris.
With Frankie Dettori, winning his 25oth Group 1, in the saddle, the daughter of Sea The Stars was the 7-4 favourite to provide her owner-breeder Anthony Oppenheimer with a third Champions Day victory in as many years following the back-to-back wins of the brilliant Cracksman in the Champion Stakes.
It was not all plain sailing for the market leader as she was hard at work halfway up the home straight - and was briefly short of room after Sun Maiden drifted across the track, leaving Star Catcher the meat in the sandwich between her and Delphinia against the far rail.