CELTIC striker Moussa Dembele has been ruled out of both legs of the Champions League third qualifying round against AEK Athens after it emerged his hamstring injury was more serious than was first believed.

However, Leigh Griffiths is set to return to the Scottish champions’ squad in their opening Ladbrokes Premiership game against Livingston tomorrow for the first time since undergoing a clean-up operation.

Dembele limped off after scoring twice against Alashkert of Armenia in the second leg of the second qualifying round last month and sat out the double header with Rosenborg of Norway.

But Brendan Rodgers, whose side will face Greek champions AEK at Parkhead on Wednesday night following their 3-1 aggregate win over Rosenborg, has revealed that the French forward is set to spend longer on the sidelines.

“The medical guys are telling me that it is probably going to be the next two to three weeks, a bit longer than we had anticipated,” he said. “That is the way it is.

“Leigh will be back in the squad. He has been out for a while. He needs to get his fitness up. He has been working hard at trying to get that up. We have kept him behind to work on that side. He will be in the squad for the weekend hopefully.”

Rodgers will continue to assess the fitness of Dedryck Boyata and Mikael Lustig, who have returned to training after playing for Belgium and Sweden respectively in the World Cup finals, before the first Athens match.

“We will see where we are at next week,” he said. “Dedryck looks great. He looks physically strong, but it is about managing that. Mika has been back in for a few weeks.

“It is that period where you are trying to win important games, but you have to be mindful that you have to get the guys in your squad up to some sort of match speed. That is the balance between the league games now and the Champions League games – to try and maximise what we can get out of them all.”