However, Griffiths scored a brace for Celtic reserves against Stenhousemuir in a friendly at Lennoxtown earlier in the week which was enough proof of rehabilitation for the Parkhead boss who has had French forward Odsonne Edouard leading the line for most of the season.
"He will be involved with the squad," said Lennon.
"Slowly but surely. He had an hour on Tuesday, he looked good so he will be in and around it.
"He is good, he is happy. He needs to stay there now and improve his conditioning. It is bit by bit but we have seen enough now to think he may make a contribution.
"We have 11 games between now and the end of December and we will be using the squad and Leigh obviously is a part of that."
Lennon also believes Scotland forward Griffiths could make a material difference to the national side, who discovered on Friday that they will face Israel in the Nations League semi-final play-off at Hampden Park in March.
The Northern Irishman said: "If fit, no question.
"When he is ready and if he is in the groove he will be a real asset for Scotland, there is no doubt about that."