Sunderland striker Fraizer Campbell admits he never thought he'd get back to playing again.

The reason lies in the two cruciate ligament injuries he suffered in the same knee, in brutally quick succession, and which led him to question whether he would ever kick a ball in anger again.

"I always tried to stay positive, but there were days when it was really hard to keep up," he told the Telegraph. "There were days when it got on top of me. There were unhappy periods when

I was pretty miserable. When I was at the training ground I made sure I was smiling, I didn't want people feeling sorry for me or making a fuss.

"The worst moments came when I was on my own with nothing to distract me. When I was around people, I was happy and positive.

"That was important, you don't want them to be worrying about how you are all the time, asking 'what's wrong?'"