Neil Lennon has hit back at suggestions from Celtic striker Leigh Griffiths that he gave him a tough time at the club during last season, after questioning the striker's professionalism.
Griffiths is out of contract at Celtic Park this summer and is hoping new manager Ange Postecoglou will offer him a new deal.
Lennon meanwhile departed as manager in February following a disastrous campaign that saw Celtic lose the league title to fierce rivals Rangers, ending a run of nine consecutive seasons as champions.
Griffiths recently claimed he was given a raw deal by Lennon, having been reduced to a bit part role on the bench for much of the season, but the former Hoops boss insisted Griffiths only had himself to blame having reported back for pre-season in an unacceptable shape.
'He let himself down,' he told BBC Scotland's Euros Breakfast Show. 'He's on full pay for the three months of lockdown and he comes back, totally out of condition and a stone overweight, when he couldn't afford to be because he hadn't played much football in the previous 18 months to two years.
'We had worked really hard with him to get him back on track and before lockdown, he was in the team and scoring goals and doing absolutely fine.
'Then he comes back completely out of condition, way, way behind any of the rest of them and for me, that was totally unacceptable.
'During the lockdown, the three months off, we opened the training ground. You couldn't come into the building but my fitness coach set up fitness training for the players every day.
'So you would come in, in groups of two, and train for an hour a day - fitness work, every day.
'Callum McGregor, Scott Brown, James Forrest, Greg Taylor, Jonny Hayes - all the lads that lived in Scotland came in. Leigh didn't come in one day, not one day during the lockdown. You can take a horse to water but you can't force it to drink.
Even after Lennon left the club in February, Celtic's caretaker John Kennedy did not offer Griffiths much playing time and Lennon wrote off the 30-year-old as not displaying enough to be picked for club nor country.
'He's saying, "I'll prove people wrong" - he hasn't proved anybody wrong. He's not at the level of being a Champions League player, he didn't get picked for Scotland - you have to ask why.
'He'll say he didn't play enough games, towards the end of the season I wasn't there, John (Kennedy) obviously felt that he wasn't in the right frame of mind or condition to play for Celtic, which is a very high standard and I don't think Leigh got anywhere near those standards over the last year or so.'