Brian O'Driscoll and Sean O'Brien have been ruled out of Ireland's World Cup warm-up clash against England in Dublin on Saturday. O'Driscoll suffered a shoulder injury in Ireland's 26-22 defeat by France in Dublin last weekend and coach Declan Kidney has left his captain out as a precautionary measure. "Brian picked up a knock against France. He's running around outside, but it was prudent to us not to put him into a contact situation on Saturday," Kidney said on Thursday. "With the game coming this week and a full tournament coming up, it just wasn't prudent to put him in the mix. Sometimes you just need to rest it up and get them out of the system." Kidney's preparations for the World Cup have also been hit by the loss of O'Brien, their most consistent performer since the start of the Six Nations. The European player of the year sustained a knee problem midway through the second half against Les Bleus, but Kidney is unconcerned by his fitness. "Sean will be fine, it wasn't prudent to include him this weekend," he said." Kidney has made seven changes to the side that started against France. In the back-line Geordan Murphy comes in at fullback to win his 70th cap, with Tommy Bowe making his first start of the series on the wing while Andrew Trimble completes the back three. Keith Earls will start alongside Gordon D'Arcy in the centre while Ronan O'Gara and Eoin Reddan form the half-back partnership. Up front Jerry Flannery is named at hooker alongside Cian Healy and Mike Ross. Donncha O'Callaghan and Paul O'Connell are paired in the second row for their 40th start together in green, with O'Connell taking over as captain. Stephen Ferris and David Wallace both start for the first time in August with Jamie Heaslip completing the backrow trio.