Striker El-Hadji Diof threatened to stab defender Anton Ferdinand in a bust-up after the midweek loss to Fulham.

The Sun reported that the pair started to fight at a post-match meal and continued the next day in training.

Diouf was upset with Ferdinand's apparent lack of effort and the former West Ham defender felt likewise.

A senior player said: "It was worse than anything I have ever seen and when they were pulled apart El-Hadji shouted that he would stick Anton with a knife.

"It started during the game but El-Hadji clearly felt it wasn't finished. It all kicked off. But the fight escalated extremely quickly and became very violent.

"At first we thought it was best to let them get it out of their system.

"But it became so vicious we feared that Anton could end up with serious injuries and El-Hadji was pulled off him.

"The squad was left stunned by what we had witnessed.

Nobody spoke. None of us were surprised when we heard El-Hadji had been sold to Blackburn."

Diouf was subsequently sold for two million pounds to Blackburn Rovers 24 hours after the incident and Sunderland players seem to be happy seeing the last of the volatile Senegalese.