Chester May Festival Day One: Changingoftheguard to book Derby ticket

can give Aidan O'Brien a perfect 10th victory in the Boodles Chester Vase Stakes (Colts & Geldings) (3.40pm) and book his ticket to Epsom on the opening day of the Chester May Festival on Wednesday.

The trials for next month's Cazoo Derby are under way and the Group Three feature on the Roodee sees another big clash between the big two racing operations, Coolmore and Godolphin.

Godolphin and trainer Charlie Appleby struck first with Coreobus's fine victory over stable-mate Native Trial in the QIPCO 2,000 Guineas at Newmarket on Saturday, with O'Brien's Luxembourg running a fine Derby trial in third. He is the current 2-1 favourite with most firms for Epsom glory on June 4.

Just behind him in the betting at around 5-1 is Appleby's , who has looked a smart middle-distance performer in the making. He won on his debut at Newmarket in the autumn and impressed again to make it two from two on his seasonal reappearance at the Craven meeting at Headquarters.

He looks a decent prospect, but on this occassion O'Brien's Changingoftheguard may lower his colours and join the likely big Ballydoyle team for the Derby.

The Galileo colt's best effort in three juvenile starts was when a neck second to stable-mate River Thames at Punchestown in September. But he broke his maiden tag with an impressive six-length success stepped up to 1m2f at Dundalk on his return to action last month.

He looks a progressive colt and can take the step up in trip to 1m4f and into Group Three company in his stride to put a dent in New London's Derby hopes.

Merseyside-born Donald McCain is more known for his successes over the jumps and particularly when winning the Grand National with Ballabriggs at Aintree Racecourse in 2011. But he also targets races at