Cox Plate and Melbourne Cup winning jockey Ryan Moore is expected to be out of action for more than a month after a barrier mishap.

The multiple English champion jockey remains in hospital awaiting the results of an MRI scan.

He was hurt when his mount, Newton's Law, reared up and became trapped under the stalls before the final race on the opening day of the July meeting.

"He's fairly comfortable, but he will be out for a while. He will be out for more than a month," his father, trainer Gary Moore, said.

"It's been a bit long-winded, but they're trying their best to sort things out for him."

Moore is the No.1 jockey to Aidan O'Brien with the trainer's son Joseph to take the ride on Archangel Raphael in Tuesday's Grand Prix de Paris at Longchamp.

The jockey won the 2014 Cox Plate on the O'Brien-trained Adelaide and the Melbourne Cup on Protectionist for German trainer Andreas Wohler.