Celtic have suspended Anthony Stokes for two weeks following his complaints about being left out of the squad to face Inverness on Sunday.
It is understood the club have instigated disciplinary action after manager Ronny Deila accused the Irishman of disrespecting his team-mates by taking to social media to air his frustrations.
The 27-year-old was left out of the 18 for the Inverness match after travelling north with the team, and he wrote on his official Twitter account: "Buzzing to be brought all the way up to Inverness with the team to sit in the stands today, lovely weather for it too.''
The former Hibernian forward followed it up by tweeting: "Who gives a f*** about wages when your not playing games! It's all about playing and contributing not picking up a wage.''
Stokes later tweeted an apology, saying: "Sorry for earlier Tweet. Hope fans can appreciate my frustration, heat of the moment.''
But that failed to prevent him becoming increasingly isolated from the Celtic first team.
Stokes has featured only twice for the Hoops this season due to injuries and suspensions and was on the bench for the Europa League clash against Ajax on Thursday.
Deila said after his team's 3-1 Ladbrokes Premiership win on Sunday: "It is (disrespectful) for the boys. We travel every week with 20 players and the manager puts out 11 and seven on the bench and there are always two left out.
"If that is harder for him than somebody else, then for me he is not a team player.
"What is important with Stokesy is that he has to show the work first before he speaks and if you do that then you always have a future.
"But so far he has been more talking than performances.''
Meanwhile, Celtic fans have been advised not to use the Istanbul Metro next week after a pipe bomb exploded near a station.
Five people were injured near Bayrampasa subway station on Istanbul's European side on Tuesday, nine days before Celtic play Fenerbahce in their final Europa League game of the season across the Bosphorus at the Sukru Saracoglu Stadium.
Foreign Office advice to Celtic fans has since been issued which says: "Istanbul police advise against using the Metro. Alternative bus lines are available."
The advice also advises Hoops supporters to avoid any demonstrations and "try not to travel alone to the stadium and avoid displaying Celtic flags/shirts in public places".