A KNIFE thug brutally slashed a Celtic fan who had earlier offered to buy him a drink.

Kevin Stillie, 32, struck Scott Paterson across the face as he stood outside a bar in Easterhouse on May 13 this year.

A judge watched CCTV footage of the attack which has left Mr Paterson scarred for life.

Stillie is now behind bars after he admitted assaulting the victim to his severe injury and permanent disfigurement.

It emerged the ex-biscuit factory worker was previously jailed for four and a half years for violence.

Mr Paterson had been in the city's Bridge Inn pub at the same time as Stillie.

He told Stillie he knew his uncle and offered to get him a drink.

But, Stillie instead quickly became aggressive and was warned by bar staff.

Mr Paterson went on to tell him: “Calm down or you will be put out.”

But, CCTV shown at the High Court in Glasgow caught Stillie then repeatedly headbutting the shocked victim.

Further footage then saw Stillie returning to the scene as the victim stood in the street.

The thug came up from behind, seemed to chat to Mr Paterson before striking him with a blade from ear to chin.

Mr Paterson initially thought he had been punched – but was forced to use his green and white hooped scarf to stem blood from his face.

The court heard he is now permanently scarred following his ordeal.

Stillie, of the city's Easterhouse, handed himself into police two weeks after the attack.

Geoffrey Forbes, defending, said: “He wishes to sincerely apologise for his conduct.

“He has left Mr Paterson with a daily reminder as to what happened.”

Lord Burns deferred sentencing for reports.