Joseph O'Brien is hoping conditions at Leopardstown do not deteriorate ahead of Battle Of Marengo's highly-anticipated return to action in Sunday's PW McGrath Memorial Ballysax Stakes.

A winner of three of his four juvenile starts, Battle Of Marengo ploughed through the Curragh mud when signing off for the year in the usually-informative Beresford Stakes in late September.

However, O'Brien is sure his mount is far more effective on a sounder surface and he would prefer for the ground not to be too testing for Battle Of Marengo's three-year-old debut.

"He's in good form and he's just ready to start off. If he runs a nice race, we'll be happy," said Ireland's champion Flat jockey.

"I would be a little but worried if the ground went very soft. There's no denying he gets through it all right, but I've always thought he was a better horse on better ground.

"He's a lovely moving horse and the day he won in Leopardstown last year on good ground, my saddle slipped, I couldn't push him at all in the straight and he still broke the track record.

"For his first run back and his first run over a mile and a quarter, you wouldn't want the ground to be too bad."

Battle Of Marengo is one of two runners for the rider's father, Aidan O'Brien.

The master of Ballydoyle has saddled six previous winners of this recognised Derby trial, with subsequent Epsom heroes Galileo and High Chaparral both on the roll of honour, as well as the incredible Yeats.

The second O'Brien runner this weekend is the Seamie Heffernan-ridden Foundry, who created a big impression when making a winning debut at Leopardstown in early November.

Joseph O'Brien said: "He only had the one run towards the back-end of last year, but he couldn't have done it any easier than he did.

"Seamus was very impressed with him and we were all delighted, so hopefully he'll run a nice race on Sunday as well, but Battle Of Marengo is obviously the form horse."

Jim Bolger has trained seven previous Ballysax winners, including the last three.

This season the pick of his two runners would appear to be Alpinist, who made a winning return to action in a heavy ground maiden at the Curragh three weeks ago.

Bolger said: "He's very well and we're hoping he can make the step up, but it won't be easy.

"He has plenty of speed and we could have stayed at a mile if we'd wanted to, but we made a decision to come for this race and go down the middle-distance route.

"I think better ground will suit him well."

Bolger also saddles Beyond Thankful, and added: "He's a little more exposed, but I'm hoping he'll also run a good race."

The six-runner field is completed by Patrick Prendergast's three-time winner Sugar Boy and the Dermot Weld-trained Imperial Concorde.