LEIGH Griffiths is undergoing “extensive treatment” to be fit for Celtic’s Champions League clash with Rosenborg in Norway next week, according to manager Brendan Rodgers.

The Hoops striker was suspended for the goalless first leg of the third qualifier at Parkhead on Wednesday night, but would have been ruled out anyway with a calf injury.

Celtic’s only other recognised centre forward, Moussa Dembele, is out until at least September with a recurring hamstring complaint.

Rodgers played midfielder Tom Rogic up front to no avail against the Eliteserien leaders and the Hoops boss now faces a wait to see if Griffiths and defender Erik Sviatchenko, who missed out with a groin complaint, will be back for the return game in Trondheim.

Ahead of a friendly at Sunderland on Saturday, where representatives of Celtic will make a £10,000 donation to the Bradley Lowery Foundation, Rodgers said: “We have to wait over the course of the weekend to see his reaction to his work outside. The same with Erik Sviatchenko. His scan was good so hopefully he will be fine too.

“It is not rest [for Griffiths]. It is a lot of extensive treatment on trying to get him fit, out on the field and seeing how his loading is to see if he is going to be fit to play.

“He needs to show that he is fit to play. He is working day and night with the medical team so hopefully we can get him back.

“He has been out on the field today which is good, but we have to see.

“There is still a wee bit of time to go before the game. We’ll see how he is over the weekend, and if he can get on to the field by Monday then there is every chance he could be involved.”

Rodgers revealed his reasoning behind not adding a third quality centre-forward to his squad, but admits he may have to reconsider.

The Northern Irishman said: “With all due respect to Scottish football, you can’t have three top strikers. You are not playing in the Premier League or a real competitive league.

“It is equally as tough [here] but in a different way. You cannot bring in another top striker because the dynamic wouldn’t work within the group, within the model of how we play, it is not going to suit us – but it is something that we have to look at.

“If Moussa is out and Leigh is up and down with his fitness then we would have to look to get one in.

“But I am not one for stockpiling players. I don’t want to bring in one for the sake of it. It needs to be the right quality and needs to be something that is right within the dynamics of the team and squad.”

The former Swansea and Liverpool boss claims the pressure is now on Rosenborg for the return game.

“The game will open up over there,” he said. “There is huge pressure on them playing at home.

“They will want to show that they are the team with the initiative and so that should open up a little more space.”