Aidan O'Brien launches a three-pronged assault in today's P.W. McGrath Memorial Ballysax Stakes at Leopardstown in a bid to claim the recognised Derby trial for a record eighth time.

Ballydoyle greats like Galileo (2001), High Chaparral (2002) and Yeats (2004) are among previous winners of the Group Three event and this year's team is made up of the highly-rated Beacon Rock Cook Islands and Idaho

Beacon Rock is the most experienced of the trio, having had four runs as a juvenile, and shaped well in finishing placed in the Beresford Stakes at the Curragh and the Autumn Stakes at Newmarket.

The son of Galileo is partnered by Seamie Heffernan, while Ryan Moore interestingly gets on board Cook Islands, who was last seen impressing in a Navan maiden in early October.

The trio is completed by the Colm O'Donogue-ridden Idaho, who was fourth in the Criterium de Saint-Cloud last autumn.

Jim Bolger has also saddled seven winners of the 10-furlong contest and runs Moonlight Magic and Theodorico

Dermot Weld 's Harzand a recent winner at Cork, and the John McConnell-trained Play The Game complete the line-up.

Weld is the leading trainer in the Leopardstown 2,000 Guineas Trial with seven previous wins and the master of Rosewell House has strong claims of adding to his tally with True Solitaire

The Oasis Dream colt was beaten a short head by O'Brien's Port Douglas in the Beresford on his final start as a two-year-old.

Weld also saddles A Likely Story while the O'Brien-trained pair of Johannes Vermeer (Moore) and Black Sea (Heffernan) and Stenographer from the Bolger yard make up the field.

The 1,000 Guineas Trial has a more open look to it, although O'Brien's Alice Springs sets the standard on the strength of her fine effort to finish second in the Breeders' Cup Juvenile Fillies Turf.

How High The Moon represents the same team, while the Weld-trained Juliette Fair will have her supporters following the handler's fine start to the season. Now Or Never is an interesting contender for Michael O'Callaghan.

The three-year-old bolted up at Galway last summer and gave smart colt Herald The Dawn a run for his money in the Futurity Stakes at the Curragh.

She disappointed on her final appearance of 2015 in the Moyglare Stud Stakes, but O'Callaghan is confident she can bounce back.

He said: "I can't wait to run her. She's done brilliantly over the winter and has been working well this spring.

"Kieren Fallon has been riding her in her work and likes the filly a lot. I know he's really looking forward to riding her.

"The Moyglare just came too soon for her after having a hard race in the Futurity. She was also growing at the time, which didn't help, so you can just put a line through that.

"If you take her run in the Futurity, natural progression from there suggests she should run a massive race on Sunday."