Leigh Griffiths back would be like £6m signing for Celtic, says Neil Lennon

Sidelined since last December as he addressed mental health issues, striker Griffiths will train throughout the close season in a bid to force his way back into first-team action for the champions.

New Celtic manager Lennon has urged the 28-year-old to “knuckle down” in his efforts to regain full fitness and match readiness but is hopeful of being able to call upon the services of the player he signed from Wolves five years ago during his first spell in charge of the club.

“We could have a £6m striker on our hands for nothing,” said Lennon. “It will be like a new signing. Leigh has missed a lot of football in the last 18 months and he’ll need to knuckle down, but he’ll have our full support.

“He’ll need to get up to speed with his conditioning. He’s working hard and we’ll see where he is football-wise.

“He’s had the club’s full support throughout this period, so it’s payback time for Leigh.”

Griffiths, who is under contract until 2022, has scored 104 goals in 202 appearances for the club and Lennon is understandably keen to restore that level of firepower to his squad for the 2019-20 campaign.

“Leigh is good at what he does,” added Lennon. “He scores goals and we want to see him back doing what he does best.”

Lennon has confirmed he plans to step up the first-team involvement of youthful trio Michael Johnston, Ewan Henderson and Karamoko Dembele next season.

Winger Johnston (20) and midfielder Henderson (19) both featured sporadically in the treble treble campaign, while Lennon handed 16-year-old playmaking prodigy Dembele his debut in the final Premiership fixture against Hearts last month.

“I am excited about them,” said Lennon. “Dembele lit the place up the other week. He is very important to the club, as are the likes of Henderson.

“Michael Johnston played in the cup final and that will be a huge shot in the arm for him. We think he’s good enough.

“It’s important for me as a manager to bring players through from the academy.

“It’s vital we develop our own. We have fantastic examples and role models in players like Kieran Tierney and Callum McGregor.

“We need new ones coming through and I believe some of them will be good enough to do that. It’s not easy. They know the requirements and the demands we will ask of them.”

Lennon hopes to conduct his incoming transfer business as soon as possible this month to ensure Celtic can hit the ground running for their opening Champions League qualifier on 9 or 10 July.

“We start pre-season training on 17 June but we will give all the international players extra time off,” he said. “It may be a case of players coming back in bits and pieces but that’s the reality of it and we understand that.

“There are far more games and, with the season we’ve just had, guys finished on 25 May with us and then are going away with their countries. They could then be playing Champions League qualifiers in early July.

“It’s hugely difficult but if you can get new players in early enough, you can subsidise that. That’s what we are looking to do at the minute.”