LEIGH GRIFFITHS has vowed to repay Neil Lennon and Celtic for standing by him during the summer, admitting that he let the club down with his lack of professionalism.

The striker was left out of Celtic’s pre-season trip to France after reporting back for pre-season out of shape, and subsequently picked up a calf injury that has kept him out of action ever since.

He climbed off the bench for his first Celtic appearance in seven months to nod a late opener at McDiarmid Park though, and he has now promised there is more to come.

“I let myself down, my club down,” Griffiths said “I let everybody down.

“Hopefully I will do well in the next few games and start repaying them.

"Of course, it has been a difficult time, but I have just been working away trying to

get my fitness back up.

"It is unfortunate that Albian got injured and gave me my chance to come back in, I took

my chance and I now I need to build on it.

“You need to keep working on the fitness, keep waiting for that break to come.

"I managed to get on the bench the last three games now, so I have done myself no harm. Now

I've got a chance over the next two weeks to get my fitness up to the same level as the boys

and come back and kick on.

“You’ve seen what I can do, and I have done it throughout my career.

"If the chips are down, I will stand up and be counted and score goals."

Despite falling firmly out of manager Lennon’s favours in pre-season, Griffiths says he never feared that his Celtic career was over.

"No,” he said. “I spoke to the gaffer at length many times and he always said as long as he is here, I will be here. I just need to keep working on my fitness and make sure that when I am called upon that I make an impact.”