Logician maintained his unbeaten record to win the prestigious St Leger at Doncaster and give jockey Frankie Dettori his sixth win in the Group One race.
The 5-6 favourite won by four lengths to give trainer John Gosden his fifth success at the meeting.
Sir Ron Priestley, ridden by 49-year-old Franny Norton, finished second with 40-1 shot Nayef Road in third.
The one-mile-and-six-furlong race was Logician's fifth win in succession.
"He's amazing. He's the favourite. There are 30,000 people here and he delivered. It's great for the sport," Dettori told ITV Racing.
"He's not short on speed. He's only run five times and it's a good horse to have, with plenty to come.
Trainer Aidan O'Brien, who had three horses in the field, was aiming for a third win in three years, but his best place was Sir Dragonet in fourth.
Dettori's five previous wins in the showpiece race came in 1995, 1996, 2005, 2006 and 2008.
Elsewhere, jockey Ryan Moore landed a treble with a win on 11-10 favourite Magical in the Irish Champion Stakes at Leopardstown.
O'Brien managed a 1-2-3 with Magic Wand and Anthony Van Dyck finishing in second and third respectively.