Unified heavyweight titleholder Anthony Joshua’s defense against mandatory challenger Kubrat Pulev, scheduled for Oct. 28 at Principality Stadium in Cardiff, Wales, is off though efforts are in the works to salvage the card by getting a new opponent on short notice, a source with direct knowledge of the situation told ESPN. Pulev’s withdrawal from the fight has not been formally announced but he suffered a right shoulder injury in training last week that was kept secret until it was clear he could not compete.