Willie Mullins' bid to dislodge Paul Nicholls as Britain's champion horse trainer was boosted by two winners on the opening day of the Aintree Festival, including Annie Power in the feature race Thursday.

Annie Power was one of seven winners for Mullins at last month's Cheltenham Festival and she was just as impressive in the Aintree Hurdle, cruising home by 18 lengths to justify her status as 4-9 favourite for the race.

That completed a double for Mullins, with Apple's Jade having already won the 4-Y-O Hurdle.

The Irishman is attempting to become the first overseas trainer to be champion trainer since Vincent O'Brien in 1954.

Mullins started the Aintree Festival trailing Nicholls in the title race by about STG 250,000 ($A460,000), and his two winners will see him almost wipe out the deficit with just two weeks of the season remaining.