Vandeek lost his unbeaten record as Inisherin ran out an impressive winner of the Betfred Supports Jack Berry House Sandy Lane Stakes at Haydock.
Sent off the 8-11 favourite, Vandeek won each of his four juvenile starts, including Group One glory in both the Prix Morny and Middle Park Stakes.
However, he was clearly toiling approaching the closing stages of the six-furlong heat with Inisherin, who finished unplaced in the 2000 Guineas last time, well in control for Tom Eaves.
After racing prominently, the 9-2 shot had plenty in reserve to run out a three-and-three-quarter-length victor over 40-1 shot Orne, with Vandeek the third-placed horse.
Inisherin does not hold an entry in the Commonwealth Cup at Royal Ascot, although he can be supplemented for the race at a cost of £46,000, with Coral making him the 4-1 favourite for that contest.