US Navy Flag put up a gutsy performance to lead home a one-two for Aidan O'Brien in the Juddmonte Middle Park Stakes at Newmarket.

The 10-1 shot, ridden by Seamie Heffernan, was always prominent in the centre of the course and saw of the challenge of his Donnacha O'Brien-ridden stablemate Fleet Review (25-1). Mark Johnston's Cardsharp (14-1) was third.

It was O'Brien's 20th Group One success after Clemmie in the Cheveley Park Stakes, but there was disappointment as O'Brien's first string, Sioux Nation, was never able to challenge after being held up in the early stages by Ryan Moore.

US Navy Flag was slashed to 20-1 from 66-1 for the 2000 Guineas by Paddy Power.

Heffernan said: "It was no surprise he ran well. I thought Ryan (Moore, on Sioux Nation) was the danger, but his horse is big and might be a little bit weak. This lad is out of a Galileo mare and that's what kicked in.

"He's a horse that's a bit gawky and looks around, so the blinkers help him focus and make the jockey's job easier.

"Aidan will take him home and have a look at him and see what shape he's in."