Jockey Joseph O'Brien is hoping the rain stays away from Leopardstown to allow Battle Of Marengo to show his full potential in the Derrinstown Stud Derby Trial this afternoon.

The Galileo colt moved to the top of Ballydoyle's Derby pecking order with a most impressive performance in the Ballysax Stakes on his seasonal return.

He now follows a tried-and-tested route by aiming to follow up in the Derrinstown, a race Aidan O'Brien has won nine times, including with subsequent Epsom Derby heroes Galileo (2001) and High Chaparral (2002).

Battle Of Marengo is currently second in the Epsom betting, behind Jim Bolger's 2000 Guineas victor Dawn Approach, and although he has shown an ability to handle testing ground, O'Brien jnr feels Ballydoyle's inmate will be even more potent on a sound surface.

He said: "I'd be hoping the rain stays away as, although he has run very well on heavy ground, he is definitely a better horse on better ground.

"One of his best performances was when he won in Leopardstown last year on good ground. The saddle slipped that day and he still broke the track record.

"I'd love to get him on a bit of nicer ground again and, hopefully, he'll get that on Sunday. He was good in the Ballysax, it was his first run of the year and hopefully he'll have come on for that.

"This isn't the be all and end all, it's his second run, and hopefully he'll come on again. I think it looks a better Derrinstown than it has for the last couple of seasons - hopefully we get some nice ground."

Just five runners go to post and the chief opponent to Battle Of Marengo appears to be the Bolger-trained Loch Garman

The son of Teofilo did not make his debut until winning at Navan last October, the form of which has worked out well, and he was turned out just a week later to land the Group One Criterium International at Saint-Cloud.

While he makes his reappearance over a mile and a quarter, Bolger is considering dropping his charge in trip after this weekend for a tilt at the Irish 2,000 Guineas.

Bolger said: "All is good with him and he doesn't mind about the ground. He's a horse with plenty of toe and he could come back (in trip) for the Irish 2,000 Guineas. He's in the Irish Derby later on."

Andrew Oliver expects First Cornerstone to benefit from his first outing since he finished fourth to the O'Brien-trained Kingsbarns in the Racing Post Trophy at Doncaster last October.

"He has developed physically and we are very happy with him," the County Tyrone trainer told At The Races.

"We had a hold-up with our gallops earlier in the year so all of my horses were quite behind and are taking a run anyway. Having said that I'm fairly happy with his preparation but I expect him to come on for the run.

"We hope he is well equipped with both speed and stamina to deal with stepping up in trip and being able to travel well and quicken."

The quintet is completed by Dont Bother Me who makes a swift return for Niall Moran having finished eighth in the 2000 Guineas, and John Oxx's Dundalk maiden winner Little White Cloud