Joey Barton, the Newcastle United midfield player, pleaded guilty today to assaulting a former team-mate in a training ground row.

The 25-year-old was due to go on trial at Minshull Street Crown Court in Manchester over the incident involving Ousmane Dabo, but changed his plea shortly before the scheduled start. He will be sentenced on Tuesday.

Barton admitted one charge of assault occasioning actual bodily harm to Dabo when they were at Manchester City. It is the third time the player has been in court in 2008, but his bad behaviour stretches back more than four years.

In April 2004 he stormed out of Eastlands before kick-off after being axed from the side to face Southampton while, in a 2005 pre-season friendly, he sparked a mass brawl in a game against Doncaster Rovers.

At a Christmas bash for Manchester City players that December, he stubbed a lit cigar into the eye of Jamie Tandy, a young team-mate. He was fined six weeks’ wages.

In May 2005 he broke the leg of a 35-year-old pedestrian while driving his car at 2am in Liverpool city centre and the following month was involved in a spat with a 15-year-old Everton fan at City’s team hotel in Bangkok. Again he was fined by City.

The bad blood with Everton fans continued in 2006 when he dropped his shorts in front of the home fans at Goodison Park. He was fined and warned by the FA for his conduct.

In February last year he made his England debut against Spain but a month later was arrested on suspicion of assault and criminal damage in an incident involving a taxi driver. However, he was later found not guilty of vandalising the car, after his cousin, Joshua Wilson, 19, admitted doing the damage.

Three months later after that incident came the fight with Dabo, and a month after that he was sold by City to Newcastle United for £5.8 million. Barton sat out Newcastle’s Boxing Day game last year as he was injured, but went drinking in Liverpool city centre afterwards.

In the early hours of December 27 he got into an argument in a McDonald’s restaurant and violence again broke out. Drunk, Barton straddled his victim, punching him repeatedly in the face. The attack was caught on CCTV. The player admitted assault and affray and was jailed for six months on May 20.