Crystal Palace captain Luka Milivojevic and on-loan Chelsea striker Michy Batshuayi had to be pulled apart by team-mates during a training ground bust-up in midweek.
The Daily Mail says the feuding duo came to blows on Wednesday after an increasingly tense training exercise got out of hand, to the astonishment of onlookers.
The angry flare-up is understood to have been triggered by Milivojevic's irritation at Batshuayi's attitude during a passing drill, in which Palace's players were asked by the coaching to test each other's first-touches by kicking the ball at each other with increasing power.
The captain took exception to Batshuayi messing about by striking the ball too fiercely and responded by kicking the ball straight at the Belgian international striker from close range.
Both players exchanged blows and Milivojevic ended up on the floor, where the scuffling continued before the pair were separated by their colleagues.
Milivojevic played for 89 minutes of Thursday night's goal-less draw at Arsenal, with Batshuayi an unused substitute, and there appears to have been no damage to Palace's team spirit as the visitors performed well and came close to registering a shock victory.
