Former England centre-back Rio Ferdinand has shared a story of when former Manchester United captain Roy Keane punched a teammate during a training session.
Keane is widely regarded as one of the best captains in United's history, but was often accused of taking things too far, sometimes even on the training ground.
Speaking on his FIVE YouTube channel, Ferdinand recently recalled when his ex-teammate got into a training-ground clash with former Red Devils player Chris Eagles, who tried to rough Keane up with a few tough tackles and was met with an unlikely response.
"I remember when Roy Keane punched up Chris Eagles one time. He (Eagles) was only (a) young kid, (taking) liberties. It was good for him, Eagles," Ferdinand said.
"Roy must have been coming back from an injury, or he didn't play, and he was playing with the reserves and the youngsters that were in there like Eagles and Lee Martin were like rats, getting in close and trying to tackle.
"He went in late on Roy once or twice and Roy said to him, 'Listen, slow down'. The ball comes in again, Eagles was trying to impress, trying to leave his mark and left a little bit on Roy again and pulled his jersey.
"Roy just turned round and went bang in the jaw. A quick short jab and I just stood there and went, 'Roy, what's wrong with you?'
"And I went inside and said, 'Roy, why are you doing that for? He's a young kid man.' And I warned him."
Keane made 470 appearances for United during his 13 years at the club, winning 17 trophies. Eagles, meanwhile, represented the Red Devils' senior side on just 17 occasions.
Click through the gallery below to see 10 infamous bust-ups between teammates!