Ally McCoist has become the last former player to criticise Leigh Griffiths.
The Celtic striker was left behind while Neil Lennon's squad travelled to France, with Lennon explaining that Griffiths had returned to training "out of condition".
His manager has since praised Griffiths for improving his fitness, and the 29-year-old came off the bench to play the final 30 minutes of his team's 3-1 friendly win against Hibs.
Rangers legend McCoist, however, believes it was "a disgrace" that Griffiths wasn't fit enough to join his team-mates in France.
Speaking on BT Sport, McCoist said: "Again, not for the first time, he’s let himself down. He’s let the Celtic fans down. And most importantly, the man who’s stood by him, he’s let Neil Lennon down.
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"It just absolutely baffles me that wee man. That wee man should be scoring goals for Celtic and playing in the Scotland team.
"I do not understand it. I just think it was a disgrace the way he came back and wasn’t in a fit enough state to go with the rest of his team-mates to France."
McCoist's comments echoed those of former Celtic star Chris Sutton, who told BBC 5 Live Sport : "Well in the first place it's a shambles, and Leigh's only got himself to blame for that.
"You think that this is a guy who got himself into the team and transformed Celtic's season. After the Rangers game there was a lot of thinking to do when they went away to Dubai.
"He (Neil Lennon) went with two up top and Leigh Griffiths, I wouldn't say that he was at his absolute best, but that partnership was so fruitful for Celtic, and that was the difference between the two sides.
"Then the season shut down, and Leigh was in a position, as all the players were, they would have had programs to stick to and adhere to, but aside from programs there's a personal pride which you take as a player where you knuckle down and you just keep yourself fit, and Leigh didn't do that.
"I've seen Neil Lennon's called him out, quite rightly so, for his postings on social media, this that and the other.
"It means absolutely nothing, and I have to say as a former player I'm disgusted with Leigh Griffiths for the way he behaved. It's unacceptable. Totally, totally unacceptable."
Celtic kick off their Premiership campaign this afternoon against Hamilton Accies at Celtic Park.
