Former Chelsea and England striker Kerry Dixon has been jailed for nine months after being found guilty of assault.
Dixon, who scored 147 goals for Chelsea, was sentenced on today at Luton Crown Court for attacking a man in a pub.
Jailing the 53-year-old, judge Barbara Mensah said the attack was "shocking and sickening to watch".
The judge said the violence was "disproportionate, unnecessary and completely over the top".
Dixon had denied attacking a fellow drinker who had been sitting on a bar stool in the Nags Head pub in Dunstable in Bedfordshire.
The assault on 38-year-old father-of-two Ben Scoble in the early hours of May 15, 2014 was caught on CCTV.
Mr Scoble, a builder, was punched off the stool and then subjected to a flurry of blows while on the floor.
The judge said the shocking footage showed how Mr Dixon launched an attack "out of the blue", which had drawn "a gasp" from jurors when first played to the court during his trial last week.
"You were not just striking him, knocking him off his bar stool, but continuing to strike him when he was on the ground," she said.
"Then you continued to pummel him on the ground."
Dixon, who played for Luton, Reading, Southampton, Millwall, and Doncaster, and earned eight caps for England.
He had pleaded not guilty to assault occasioning actual bodily harm.
He alleged he had acted in self defence, however, Dixon, from Dunstable, was convicted by a jury after a five-day hearing with the judge describing the attack as "completely unprovoked".
The pair's first altercation was in the pub's toilet and the judge accepted Dixon's version of events that Mr Scoble had "made some comments" to the ex-striker, which were disparaging.
Dixon, on that occasion, told him to "leave it out", and nothing more was said.
However, their paths crossed again when this time Mr Scoble had sat in Dixon's seat at the bar - something the judge said could only have been "a minor irritation".
Dixon again exchanged words with Mr Scoble, and then launched his assault.
The judge said: "At worst, on your account, all he says to you after this brief exchange that he ought to sit somewhere else, is f*** off, fatso."
She added: "It's absolutely clear to me, if he did say those words - because this was CCTV without words - he didn't move, seek to strike, or get off the chair.
"You claim you had a serious fear of being glassed because of an incident when you were the victim of an unprovoked glassing (in the past).
"Why go over to Mr Scoble in that case, if he had a glass in his hand?"
Judge Mensah went on: "Out of the blue, as we see on CCTV, we see you still very annoyed immediately strike Mr Scoble."
"You were annoyed and clearly going to teach him a lesson."
She said the footage showed Dixon's victim floored with the second punch, and then several kicks rained down "about his head".
Judge Mensah added: "It was shocking and it was sickening to watch."
Before sentencing, Dixon, carrying a black holdall in expectation of today's sentence, told reporters "Whatever will be, will be."
In the court, his QC Mark Wyeth referenced a letter from the Professional Footballers' Association (PFA) in support of Dixon stating his client had got himself into a programme to tackle his problem with "gambling, and associated matters".
He said Dixon was also heavily relied upon by his "aged parents, who do not enjoy good health".
"His father had a heart attack and his mother has terminal cancer," added Mr Wyeth.
The barrister went on: "There's a great deal of good in this man and a great deal of goodwill towards him."
He said that following the assault, Dixon's media work commitments had dried up and to make money he had taken up work as a labourer to make ends meet for him and his partner.
Mr Wyeth said the former footballer had suffered depressive illness but was now "addressing the difficulties he's had with various problems".
Judge Mensah said she accepted Dixon had shown "genuine remorse" for the attack.
But, in the opening lines of her sentence, she told Dixon, wearing a purple shirt, tie, and dark suit, he would be immediately going to jail.
"I said to the jury at end of the trial that this was a serious offence," she said.
"So serious, I consider a starting point a custodial sentence, and there's nothing that has made me feel any different.
"If ever there was a confrontation in a pub where violence did not need resorting to, this must have been it."
Speaking outside court, Mr Wyeth said both the PFA and Chelsea had been "very supportive" of Dixon.
"He's got himself into a programme, finally, of sorting out his gambling issues and the residual debt," he added.
He said Dixon, who for many years had commanded the salary of a professional footballer playing at the highest level, was now renting "a council house".