Highlight on the card is the Grade 2 Prix Murat, often seen as a prep race for the prestigious Grand Steeplechase de Paris scheduled for the first Sunday in June.
O'Brien has been cleared to have his first runners of the season in Britain as overseas runners will be allowed to run in the Coronation Cup, 2,000 Guineas and 1,000 Guineas.
EXCLUSIVE BY MATT HUGHES: Racing has suffered another financial blow with Derby sponsors Investec demanding a rebate on their £3million-a-year deal due to the event dropping down to one day.