Sealiway, ridden by Mickael Barzalona, won the Champion Stakes as Oisin Murphy claimed his third consecutive jockeys' championship crown at Ascot.
Cedric Rossi's Sealiway was sent off at 12-1 and stole the lead from Adayar with two furlongs remaining.
The French-trained colt broke away with only runner-up Dubai Honour (6-1) managing to go with him.
Murphy's treble was confirmed with William Buick unable to close the gap after he finished fifth on Adayar.
Murphy had a three-winner lead in the title race coming into Champions Day, but saw that gap cut to two when Buick rode Creative Force to victory in the British Champions Sprint Stakes earlier in the afternoon.
The Champion Stakes result put the jockeys' championship out of Buick's reach, however.
Sealiway's victory followed his fifth place at in the Prix de l'Arc de Triomphe 13 days ago, and a second in the French Derby.
On Saturday, the three-year-old was followed by Dubai Honour in second and 40-1 shot Mac Swiney in third. Favourites Mishriff and Adayar came home in fourth and fifth respectively.
Barzalona, who won the Derby in 2011 with Pour Moi, said: "It's great to be back in the big time and be with this horse since the beginning. He deserved to prove his talent like he did today.
"I thought I was always going to hold Dubai Honour when he didn't pass me straight away."
Murphy said he was "over the moon and thrilled to get it across the line" in the jockeys' championship.
"Thank you to my family and everyone - I've got a massive support group," he said.
"The last week I've had a lot of people on my side. Frankie Dettori has been there every day making sure my spirits are up and I was riding off instinct as normal, which is key.
"You need to make every ride count and I was running out of opportunities. I held it together, thankfully, in the end."
Champions Day treble for Jim Crowley
In the day's other races, 16-1 chance Eshaada claimed the British Champions Fillies & Mares Stakes in a thrilling photo finish ahead of Ralph Beckett's Albaflora to seal the Group One honours for jockey Jim Crowley.
Crowley then found success again with 2-1 shot Baaeed, who maintained his unbeaten record as he edged out Palace Pier and popular mare Lady Bowthorpe in a close finish to the Queen Elizabeth II Stakes.
Crowley said: "He just keeps on getting better. He's come a long way in a short space of time and he's a proper champion."
Capping a fine day at Ascot for the the Shadwell Estate team, Crowley later sealed a Champions Day treble on 7-2 chance Aldaary in the Balmoral Handicap.