Review leopardstown 14th Apr Battle Of Marengo kept his Derby prospects firmly intact with a highly satisfactory victory on his return to action in the PW McGrath Memorial Ballysax Stakes at Leopardstown.Aidan O'Brien's 8-13 favourite, completing a four-timer, was settled in fourth for much of the way and came to challenge for the lead at the top of the straight in the Group Three contest.Joseph O'Brien was at pains not to give him a hard time, and the son of Galileo forged clear in the final furlong to beat Sugar Boy by a length and three-quarters.It was a big day for the O'Briens, who landed a treble including an eyecatching success with Declaration Of War, who imposed his class on the Heritage Stakes on his seasonal bow.He was sent past Bold Thady Quill at the furlong pole in the Listed contest and with favourite Sweet Lightning proving a disappointment, the 6-4 chance powered clear to score by two and a half lengths.The Ballydoyle team also won with Justification (5-2 favourite) in the Leopardstown Club Members Handicap.Rawaaq (6-1) booked her Classic ticket with a stylish victory in the Leopardstown 1,000 Guineas Trial in the colours of Sheikh Hamdan.Dermot Weld's filly quickened up nicely to join What Style a furlong out and Pat Smullen did not have to get too busy to beat his rival by a length and a quarter.Owner Andrew Tinkler looks set to make his mark again this season with horses trained by Tommy Carmody judged on the manner of Fort Knox's victory in the Leopardstown 2,000 Guineas Trial.Winner of a Newbury maiden for Richard Hannon last year, the full-brother to English and Irish 2000 Guineas runner-up Dubawi Gold (7-1) swept down the outside from the rear under Johnny Murtagh to win by a length and three-quarters.Jim Bolger put another on the board in the Irish Stallion Farms EBF Maiden when juvenile debutant Focus On Venice (2-1) led inside the final furlong under Kevin Manning and held Michaelmas's charge by a head.