Aidan O'Brien is on the cusp of Bobby Frankel's Group One record haul after US Navy Flag's win in the Dewhurst Stakes at Newmarket.

For good measure, the trainer saddled the next three horses home in the seven furlong (1400m) race on Saturday (Sunday (AEDT).

The win took O'Brien to 24 winners for the calendar year, one short of the late Frankel's tally.

US Navy Flag added to his Middle Park Stakes win with an impressive 2-1/2 length victory under Ryan Moore with Mendelssohn, Seahenge and Threeandfourpence second, third and fourth respectively.

The previously unbeaten Expert Eye was always in US Navy Flag's slipstream, but the 4-7 favourite dropped back through the field and finished last of nine runners.

"He is a very good Middle Park winner and I think he was overlooked a bit," O'Brien said..

"I suppose we're lucky to have a colt who has pace enough for six (furlongs) and it looks as though he's a good chance of getting a mile."

O'Brien said the Breeders' Cup was a possibility.

The trainer came within in a half neck of another Group One success when Johannes Vermeer finished second to Gailo Chop in Saturday's Caulfield Stakes in Melbourne.

He has runners in two Group One races at Woodbine in Canada on Sunday.