Derby-winning jockey Martin Dwyer looks set to be out for the rest of the season as he prepares for knee surgery.

The 46-year-old, who partnered Sir Percy to Epsom Classic glory in 2006, suffered a torn ACL last month in a fall on the gallops and will undergo an operation in the next couple of weeks, according to trainer Muir.

Dwyer, who is married to Muir's daughter, Claire, was preparing to ride the classy Pyledriver in the Longines Dubai Sheema Classic when he was hurt riding out for Brian Meehan.

The rider, an ardent Everton fan, twisted his knee when a leather iron broke, and Muir, who jointly holds a licence with Chris Grassick, suspects he will be out for the long haul.

"He's not playing for Everton at the minute – although they might need him," quipped Muir.

"He is having plenty of physio down at Oaksey House (rehabilitation and fitness centre in Lambourn) before the operation, because they wanted to take the inflammation away as much as they could before they operate.

"He is having the operation in early May. He is definitely having the ACL operation. He is a bit down, because he can't do anything. He is in a leg brace, what can you do?

"He is a bit fed up with life and Everton are playing so well! The fact that Liverpool are doing well doesn't help his mood, either."

Frankie Dettori deputised for Dwyer when Pyledriver suffered a luckless passage in being beaten a length by Shahryar in the Sheema Classic at Meydan and he looks set to retain the ride when the five-year-old bids to defend his Coronation Cup title at Epsom on June 3.

Muir said he could not estimate a timeframe for how long the stable jockey will be sidelined.

"I can't answer how long he will be out for," admitted Muir.

"It depends on how quickly he will recover, but he is a pretty tough lad. I think he has to have it screwed or stapled and they will see what the damage is when they operate. It will take a little time to recover.

He added: "Pyledriver is still on course for Epsom. That's the plan. We are working hard."