Boxing: Back injury scuppers Calzaghe's title bout

Joe Calzaghe has withdrawn from his International Boxing Federation world light-heavyweight title challenge against Glen Johnson next Saturday.

His promoter Frank Warren said the undefeated Welshman, who was stepping up to 175lb for the first time after nearly seven years as World Boxing Organisation super-middleweight champion, sustained a back injury in sparring last week. Calzaghe has had treatment but has not responded to it.

The 32-year-old was arrested last week but released without charge after an alleged incident at his home in Wales. But Warren stressed that Calzaghe's personal problems did not influence the decision. "Due to the severity of the injury and despite undergoing intensive physiotherapy treatment he is still in great pain," Warren said. "There was no way he could get in the ring with Johnson, who is a great champion and is expected to give Joe the toughest test of his career." Warren hopes to reschedule for next month.

In Las Vegas, middleweights Bernard Hopkins and Oscar De La Hoya both won on points on Saturday and are expected to go head-to-head on 18 September for a reported purse of more than $30m (£16.3m).

Hopkins beat the IBF contender Robert Allen while De La Hoya, making his middleweight debut, had to rally to beat the German Felix Sturm to claim the World Boxing Organisation title on the same card.