It's trials day at Leopardstown and six go to post for the big Derby test of the day, the PW McGrath Memorial Ballysax Stakes.

Aidan O'Brien's Beresford Stakes winner Battle Of Marengo, unbeaten in his last three starts, gets his season under way in the Group Three test, but he is sure to have his mettle tested.

Sugar Boy is also unbeaten in his last three, culminating in a Listed success at this track in November, while Jim Bolger has saddled the last three winners of this race and his Alpinist has the benefit of a recent run, having scored at the Curragh last month.

Snow Queen looks the pick of O'Brien's two runners in the other Group Three on the card, the Leopardstown 1,000 Guineas Trial Stakes.

Twice a winner in her juvenile season, there will be plenty expected of her, though Rawaaq fared well enough in Pattern races last term to be a threat, while Pop Art, Hint Of A Tint and Bunairgead all promise much after maiden successes.

The colts get their chance in the Leopardstown 2,000 Guineas Trial Stakes, where The United States gives O'Brien another strong chance after winning a maiden at the Curragh on his sole start last term.

Dibayani reopposes after going down by a head in that race, and he looks a live danger as he ended last season with a fair third to Battle Of Marengo.

Declaration Of War was lightly raced in his first season in Ireland last term, but he showed plenty of promise and is likely to figure in the Heritage Stakes.

O'Brien's charge is a massive horse, though, and if he needs this outing, then Irish Lincolnshire hero Sweet Lightning could be hard to stop.

The meeting gets under way at 2.05 with the Irish Stallion Farms EBF Maiden, where Michaelmas, Glory Boy and Focus On Venice catch the eye.