CELTIC striker Leigh Griffiths says he is ready to get back to his best after coming through the dark days of illness and injury that have plagued him of late.

The forward climbed off the bench to score the third goal in his side's 3-0 win at Hamilton from a free-kick, and his celebration was a cathartic release after weeks of frustration on the sidelines.

"It is always nice to be back on the pitch," Griffiths said. "It has been a frustrating five, six weeks for me in which I have been trying to build myself back up to full fitness. To come back and score like that was great.

“It was dark times. There was a lot of frustration going into it. But you just have to get on with it, you have to do your rehab properly. It didn’t help that I was ill for 10 days, that took up a chunk of my recovery time. But no, it was good to be back in the team and hopefully I’ll be back firing on all cylinders."

The initial injury suffered by Griffiths was a different calf problem from the reoccurring ones that have dogged his career, but he feels the time out to focus on his fitness was required in any case.

“These things happen [the calf injury]," he said. "It wasn’t the same area as I have had trouble with before, it was a different area.

“Speaking with the management and the sports science staff there is no secret that I was a bit heavier looking, but over the course of the six weeks I have managed to drop a lot of the weight and I feel a lot sharper. If I can continue working hard on the training pitch then when I get my chance I can take it."

He is now hoping to have a similar impact against Rosenborg on Thursday night in Norway after scoring with his first touch in Hamilton.

“The manager pulled me aside with about 20 minutes left and said ‘go on and do what you can’," he said. "I think it was actually my first touch that I scored with! I was on the pitch for five, six minutes before I touched the ball. And I think I was on the touchline waiting for about five, six minutes before that.

“Listen it is always nice to come back with a goal. It is an important three points and we will look forward to Thursday now."