The brilliant career of the 2,000 Guineas winner King Of Kings appears to be over. The Aidan O'Brien-trained colt suffered a serious knee injury when finishing last in Saturday's Epsom Derby and O'Brien reported yesterday: "He's unlikely to race again."

King Of Kings injured his off-fore knee, the same one that was operated on last autumn. "It's a recurrence of an old injury but it's worse this time," O'Brien said. "We don't know how he did it but it's a devil because he's such a talented horse."

Second Empire has come out of the Derby in better shape but O'Brien yesterday agreed with Michael Kinane that the colt didn't stay the mile and a half. "We'll sit down and talk about where to go next but he could have a break," O'Brien said.

Saratoga Springs finished three places behind Second Empire in tenth and will also be given a break, having run in two Derbys in a week. O'Brien reported his Oaks winner Shahtoush as being on target for the Irish Oaks.