Not good 
http://www.sufc.premiumtv.co.uk/page/News/NewsDetail/0,,10418~1082626,00.html

Bryan Robson last night confirmed that summer signing Billy Sharp sustained a broken hand in the 2-0 friendly victory over Portadown, during the tour of Ireland.
Robson said, "Unfortunately Billy has broken his hand and he has had it put in a cast today - there was no point in risking him against Rotherham."
Bryan was quick to dispel fears of a prolonged spell on the sidelines for the striker and indicated Sharp should still be available for selection.
He commented, "He can play with the cast on, although we will have to see how he goes in training, it will depend on whether the soreness from the break has gone.
"Everything will be taken into consideration before deciding on possible selection - places are still up for grabs."
http://www.sufc.premiumtv.co.uk/page/News/NewsDetail/0,,10418~1082626,00.html