No Heretic beat Nakeeta in a photo finish to win the Chester Cup in his first Flat race for 972 days.
Jockey Jamie Spencer got the 11-1 chance up to win by a short head for trainer Nicky Henderson.
Henderson is more used to training horses over the jumps and No Heretic had his first run since September 2013 when third in a hurdle race last month.
His injuries have included one suffered jumping a fox in winning at Leicester in 2011, entailing a year off.
"Then he did a tendon and needed nearly 1,000 days off. We thought we'd persevere as he's got a lovely pedigree and it's paid off," said Alex Cole, racing manager to owners Jim and Fitri Hay.
Henderson, indicating the horse may run in the Ascot Stakes at Royal Ascot next month, said: "He was a wounded soldier but it is great to see him come back."
Meanwhile, six-time champion jockey Kieren Fallon was back among the winners at the age of 51.
Fallon, who has spent recent spells riding in the United States, scored on Sir Maximilian in the five-furlong conditions stakes.
The gelding, trained by Ian Williams, could now offer Fallon the chance of another victory at Royal Ascot next month.
Earlier, the 8-15 favourite Somehow eventually prevailed, coming through late to win the Cheshire Oaks, under jockey Ryan Moore for trainer Aidan O'Brien.
Analysis - BBC correspondent Cornelius Lysaght
"Nicky Henderson has done it again. Although always brilliant at it, the master trainer has really excelled in recent months at getting horses not just back from injury, but back from injury to the top or somewhere near it.
"Think Sprinter Sacre, My Tent Or Yours, Simonsig and now think No Heretic. The eight-year-old, delivered with perfection by Jamie Spencer, narrowly beat Nakeeta in yet another highly-competitive staging of the Chester Cup. Some achievement."