British Champions Day: Churchill among Aidan O'Brien's hopefuls at Ascot

O'Brien has trained 24 Group or Grade One winners in 2017

Churchill and Highland Reel are among the leading hopes for record-chasing trainer Aidan O'Brien on British Champions Day at Ascot on Saturday.

Dual Classic winner Churchill will contest the Queen Elizabeth II Stakes for O'Brien, who is one short of the record for Group One wins in a year.

O'Brien runs Highland Reel and Cliffs Of Moher in the Champion Stakes against John Gosden's favourite Cracksman.

But Ulysses, trained by Sir Michael Stoute, will miss the big race.

Stoute will rely upon Irish Champion Stakes runner-up Poet's Word, while Richard Hannon saddles Barney Roy, who was runner-up to Churchill in the 2,000 Guineas before gaining revenge in the St James's Palace Stakes at Royal Ascot.

Churchill will be joined in the QEII by stablemates Lancaster Bomber and Sir John Lavery with prolific Group One winner Ribchester, trained by Richard Fahey, among the opposition.

The six-race Ascot card, which includes four Group One contests, is Britain's richest raceday with more than £4.3m in prize money on offer.

Harry Angel and last year's winner The Tin Man are leading contenders in the Sprint Stakes, where Caravaggio represents O'Brien - whose leading hope in the Fillies and Mares Stake is Hydrangea.

O'Brien has a chance earlier on Saturday to equal the record of 25 top-level wins set by the late American trainer Bobby Frankel in 2003.

The 48-year-old Irish trainer has the favourite Johannes Vermeer in the Caulfield Cup in Australia (06:30 BST).

O'Brien said he would be honoured to break the record, but is modest about his achievements.

"Everybody works close together and it's a big team effort. There are a lot of links in the chain; and so many people involved long before the horses are even conceived," he said.