The former Hibernian, Burnley and Wolverhampton Wanderers striker underwent surgery to repair damaged ankle ligaments in April and has endured a slow road to recovery. However, after working under fitness coach Claudio Donatelli, the £12 m signing is ready to return.
Paolo Di Canio, the Sunderland manager, said: "The lad is full of energy and enthusiasm. Every day he works with Claudio he's saying 'I can score a goal, I can score a goal'.
"It's typical of a hungry player, but that is positive. In the next few days, I'm going to gradually let him join the team for some part of the training session. That will give him an extra lift. It's a good step forward for him. He's obviously a player who can do a good job for us."