Aidan O’Brien fires a twin assault in a bid to extend his remarkable record in the P.W. McGrath Memorial Ballysax Stakes at Leopardstown on Saturday.

The Ballydoyle handler has farmed the Derby trial over the past couple of decades, with subsequent Epsom winners Galileo (2001) and High Chaparral (2002) among his 11 previous winners.

This year O’Brien saddles Bluegrass and Scriptwriter, who were both last seen in action on Dewhurst day at Newmarket in October.

Bluegrass, the choice of Ryan Moore this weekend, finished fourth in the 10-furlong Zetland Stakes, while Wayne Lordan’s mount Scriptwriter was fifth in the Group Three Autumn Stakes over a mile.

Of Bluegrass, who is a son of Galileo out of Group One-winning sprinter Quiet Reflection, O’Brien — who struck with Bolshoi Ballet 12 months ago — said: “He was just a bit green at Newmarket, it took a while for the penny to drop and he has a lazy way of going.

“He didn’t run too bad in the Zetland after never travelling. Newmarket can be like that if you don’t know your job.”

The highest-rated horse in the field is Buckaroo, who rounded off his juvenile campaign with a fourth-placed finish in the Group One Criterium de Saint-Cloud, the form of which was boosted by runner-up Stone Age earlier this week.

His trainer Joseph O’Brien, whose 2017 Ballysax winner Rekindling went on to claim Melbourne Cup glory, is keen to discover whether his latest candidate can make up into a realistic Derby contender.

“We aim to go down the Derby path, all being well in the Ballysax,” said the Owning Hill handler.

“He got himself in a bit of trouble on both of his last two runs by being a bit lackadaisical early on.

“In France, it was a shocking messy race and he was last or second-last most of the way and stayed on well but it was too late. That’s something that hopefully maturity will address.

“He would stay well, but I don’t think he’ll go further than a mile and a half.”

Like his father, O’Brien has a second string to his bow in the form of Swan Bay, who was not too far behind a potential Ballydoyle star in Luxembourg in September’s Beresford Stakes at the Curragh.

The trainer added: “We think Swan Bay is a horse who will stay well and we’ll see how he goes in the Ballysax and take it from there.”

Other contenders include Dermot Weld’s Duke De Sessa and the Donnacha O’Brien-trained Piz Badile, who were split by just half a length when first and second in the Eyrefield Stakes here in the autumn.