Andre Ward has been forced to postpone his super-middleweight bout with Kelly Pavlik after suffering a shoulder injury.
Ward was due to defend his WBC and WBA titles against fellow American Pavlik next month, but this fight is expected to be put back until the spring after he injured himself in training.
He wrote on Twitter: "Thanks For The Well Wishes. Minor Setback. Will Be Back In The Ring Shortly. God Bless."
Ward's injury could disrupt Carl Froch's plans as he is hoping for a rematch next year after dropping a decision win to the Oakland man in the final of the Super Six tournament.
The postponement will also prove frustrating for Pavlik, who has been steadily building towards a major fight following a brief spell away from the sport.
Pavlik has held world titles at middleweight, but he has relaunched his career in the higher division after defeats by Bernard Hopkins and Sergio Martinez.