Seamus Heffernan has picked up the ride on Risk Material in Sunday's Budweiser Irish Derby after Christy Roche's surprise decision to switch from the Aidan O'Brien team of horses to the Charles O'Brien-trained Campo Catino for the big race.

Speculation as to what Roche would ride ended yesterday when he committed himself to Campo Catino, a 16 to 1 shot with Ladbrokes. Roche, in his last season riding, has already won the Derby three times, with Assert (1982), St Jovite (1992) and Desert Prince last year.

Considering the widespread success the champion jockey has had on Ballydoyle trained horses in the last few years, it's an interesting switch. But Aidan O'Brien said: "We have never been rigid about jockeys and Christy's view is that our horses won't handle the soft ground as well as Charles' horse. I've spoken to the owners and told them Christy's decision."

O'Brien added that the forecast soft going will be of no help to any of his Derby runners. The 50 to 1 shot Desert Fox will be the mount of Kevin Manning, while Walter Swinburn was booked for Saratoga Springs earlier in the week.

O'Brien also hinted that because of the ground he may withdraw Kitza and Star Begonia from tomorrow's Pretty Polly Stakes and keep them for the Irish Oaks.