The Aidan O'Brien-trained Yucatan has been given a 2.5kg penalty for the Melbourne Cup after his dominant win in the Group Two Herbert Power Stakes at Caulfield.

The penalty moves Yucatan to 54.5kg in the Melbourne Cup weights and 24th in the ballot for the rich 3200m-handicap at Flemington on November 6 which has a field limit of 24.

The Herbert Power win also earned Yucatan a ballot exemption into Saturday's $5 million Caulfield Cup (2400m) in which he carries his original weight of 52kg because he could not be penalised.

Michael Walker has been booked for the Caulfield Cup ride.

Yucatan was the $4.50 Caulfield Cup favourite on Monday ahead of the declaration of the final field on Tuesday, while the horse was equal $9 favourite for the Melbourne Cup along with Godolphin import Avilius.

The highest Melbourne Cup penalty given to previous Herbert Power winners had been 2kg.

"Yucatan's win on Saturday was incredibly impressive, and a significant step up on his previous form in Europe this year," Racing Victoria's chief handicapper Greg Carpenter said.

"While the official winning margin on Saturday was 1.25 lengths, he was more than six lengths in front at the 100-metre mark before his jockey James McDonald eased him down.

"Yucatan will meet significantly stronger opposition in the Melbourne Cup, but the absolute dominance of his Herbert Power win demands a significant penalty."