Ryan Moore is bidding for his third Classic of the season when Giovanni Canaletto lines up in the Derby at Epsom.

Narrowly out of luck on his 1000 Guineas winner Legatissimo on Friday in the Oaks, Moore has completed a 2000 Guineas double on Gleneagles already this season and was a fraction away from going for the clean sweep.

Widely regarded as the best jockey riding today, he has cemented his association with the Aidan O'Brien and the Coolmore operation in fine style.

However, in a year without a clear-cut Derby contender, there was plenty of speculation as to what he might ride in the great race on Saturday (Sunday (AEST) until the money came for Giovanni Canaletto and his jockey confirmation swiftly followed.

Having looked promising when winning his maiden late last season, he missed an intended run at Chester only to be beaten on his reappearance by the filly Curvy in the Gallinule Stakes.

"The favourite (Golden Horn) is very good, but this lad's open to considerable improvement and I feel if he comes forward from that run, which I'm pretty sure he will do, I'm sure he'll run well," Moore told Channel 4 Racing.

Golden Horn is the only unbeaten horse in the race and beat stablemate Jack Hobbs in the Derby.

Previously Jack Hobbs was favourite for the race as Golden Horn was not originally entered.

Trainer John Gosden will walk the course to make sure the ground is not too fast for Jack Hobbs.

Another trainer who would like to see rain is Andrew Balding for Elm Park, third in the Dante and one of only two Group One winners in the field, the other being the French raider Epicuris.

One of the likely outsiders is Moheet, who will be champion trainer Richard Hannon's first runner in the race.