It was going to take more than a badly-bruised ankle to keep champion jockey Jim Cassidy out of the reckoning for another Group One Epsom Handicap win at Randwick on Saturday.

Cassidy twisted his left ankle when he struck it coming out of the barriers in a race at Canterbury on Wednesday.

The 49-year-old, who won the Epsom on Excellerator in 2002, declared he would be fit for the showpiece meeting as he limped out of Canterbury and was true to his word when he rode in a barrier trial at Rosehill on Friday.

"I said I'll be right and I'll be there," Cassidy told AAP.

"It's pretty black and sore but I'll be right."

Cassidy rides the John O'Shea-trained Lightinthenite in the Epsom as well as the Chris Waller-trained Kelinni in the Group One Metropolitan.

"They are both live lightweight chances and in these big races you always want a bit of luck," Cassidy said.

Cassidy has already been a significant player in the Sydney spring with a Group Two win on Longport in the Tea Rose Stakes and two Group Three victories on Tagus and Steps In Time.

And the Hall of Fame jockey, who remains as competitive as ever, is keen to make his mark during Sydney's biggest spring meeting.

"These are the days when you want to come out and fire up," Cassidy said.

"That's what it's all about."

Gai Waterhouse is chasing a record-equalling seventh Epsom victory and Fat Al, one of her three representatives, has been the best supported runner since Wednesday's barrier draw.

Fat Al has firmed from $5 into outright favourite at $4.60 ahead of George Main Stakes winner Shoot Out ($5).

Tommy Berry chose to ride Fat Al over stablemates Wild And Proud and Kontiki Park.

"There wasn't much between them," Berry said.

"I think it's going to be a very competitive race but this horse, Fat Al, just has the class edge on the other two I think."

Waterhouse's runners all have the 52kg limit which ruled out her No.1 stable rider Nash Rawiller.

Rawiller could spoil the party for Waterhouse as he partners the Chris Waller-trained 2010 Doncaster winner Rangirangdoo.

"He's coming off a very creditable run the other day running second to Shoot Out who we meet (half a kilo) better at the weights," Rawiller said.

"I won a Doncaster on him before, he loves the Randwick mile and it would be fitting for the horse if he could come out and win the Epsom on Saturday.

"His age and body is catching up with him but his will to win and compete is still there and that's the most important thing. That's what makes him as good as he is."