Celtic left-back Emilio Izaguirre required stitches in his ear following team-mate Nadir Ciftci's reaction to a challenge during training.
Coach Ronny Deila revealed that the Turkish forward – who missed the first six games of the Scottish Premiership campaign due to a ban for biting Dundee's Jim McAlister while a Dundee United player - lashed out at the Honduran in a training-ground spat.
The incident follows another show of ill-discipline when Kris Commons launched a frustrated tirade at assistant coach John Collins after being substituted in last Thursday's Europa League defeat against Molde.
However, Deila insisted the issue between Izaguirre and Ciftci has been dealt with internally and both players will be available for the League Cup clash with Hearts on Wednesday.
"It happens all the time," Deila said on Tuesday.
"We want intensity in training. It was a tackle and a reaction and he [Izaguirre] got hit in his ear.
"He had to get it stitched and he's fine for [Wednesday's game]. It was a reaction from another player to a tackle.
"I always say to my players I want 100 per cent – they are very good at that.
"Sometimes it gets a little too hot and [on Tuesday] there was an incident but I have talked with both players and everybody is ready for [the Hearts game].
"Nadir was the player who reacted. We have sorted it inside, we are finished with it and we move on."
