On his final appearance of the season Saint Estephe was ridden by Lester Piggott and started odd-on favourite for the Prix du Conseil de Paris and finished third behind Jupiter Island and Baby Turk.
In the Prix Ganay on 4 May he started odds-on favourite but was beaten a short head and half a length into third place behind Baillamont and Mersey with Triptych in fourth.
On 5 June Saint Estephe and Triptych represent France in the 81st running of the Coronation Cup over one and a half miles at Epsom Racecourse.
After being restrained at the rear of the field he moved up on the outside to track the leaders early in the straight and gained the advantage from Triptych inside the final furlong.
[3] Saint Estephe attempted to add a second Group One victory a month later in the Grand Prix de Saint-Cloud but was beaten two lengths into second place by the German colt Acatenango.
[3] In the official International Classification for 1985 Saint Estephe was rated the ninth-best three-year-old colt in Europe in the 11 furlong+ division, thirteen pounds behind Slip Anchor.