Hills was found guilty of careless riding aboard Polinesso - trained by his father, Barry, - who dead-heated for third place in the penultimate race.
Polinesso was demoted to fourth place and Hills was suspended for three days, 26, 27 and 29 July, meaning that he will not be able to partner Geoff Wragg's four-year-old at Ascot on Saturday week.
Hills's agent, John Robertson, could not say whether the jockey would appeal against the ban and Wragg has yet to make plans for a replacement.
Pentire, ridden by Hills when beaten a neck by Lammtarra in the race 12 months ago, is Coral's 11-4 favourite to gain compensation.
Hills had opted to ride the four-year-old ahead of his Derby winner, Shaamit. Pat Eddery was yesterday confirmed as Shaamit's new partner, leaving the Irishman, who has frequently ridden for Wragg, unavailable for Pentire.
Eddery was due to ride Shaamit in Sandown's Eclipse Stakes until connections decided not to contest the Group One prize. But he gets a second chance to link up with the colt following the defeat of another regualr mount, the Oaks winner, Lady Carla, in Sunday's Irish Oaks.Reuse content