Birr Castle posted a career-best as he went down narrowly to G1 winners Ace Impact and Al Riffa in the G2 Prix Guillaume d'Ornano at Deauville, France, on Tuesday, 15 August.
Stepping up in class after a Compiegne Listed victory last month, the Andre Fabre-trained colt raced in second of the eight runners for much of the 10-furlong contest under Mickael Barzalona.
Birr Castle was joined by Ace Impact as the duo swallowed up pacemaker Cambronne entering the final furlong, with the Prix du Jockey Club winner asserting soon after to win by three quarters of a length. Al Riffa closed between horses to take second, a head in front of Birr Castle in third.