The attack took place in the beer garden of The Alma pub in West Street, Conisbrough between 8.30 and 9pm on April 29 last year.
During a hearing at Sheffield Crown Court this morning, Stephen Welch, prosecuting, explained how defendant, Ben Redfern, walked over to a group of people and quickly became verbally abusive towards one of the women in the group.
Mr Welch said: "The defendant, who was new to them, for some reason became abusive towards one of the women. Her boyfriend intervened eventually.
"He spoke to the defendant and asked him to desist. At that point, without provocation, the defendant throws a single punch at the complainant. It staggers him, but it doesn't make him fall to the floor."
Redfern's victim suffered a fractured cheek bone in the attack, for which he needed to have metal plates fitted, the court heard.
The victim said the attack had affected his confidence, had caused him to put on weight because of not being able to go to the gym as a result of his injury and had resulted in him taking a week off work.
Redfern, of Lindrick Close, Conisbrough pleaded guilty to one count of grievous bodily harm at an earlier hearing.
Andrew Swaby, defending, said Redfern, aged 26, had raised almost £2,000 in compensation for his victim to show remorse for his actions.
Judge Roger Thomas QC said: "2,000 is way short of what it's worth, for this serious an injury. Quite frankly, £5,000 is the figure I had in mind for this."
Instead of sentencing Redfern today, Judge Thomas said he would adjourn the case until March 2 this year to allow Redfern time to raise the £5,000.
Judge Thomas said: "If I see £5,000 in your solicitor's account then we'll see where the case actually goes."
He warned Redfern: "I'm not saying I'm not sending you down, I might. Because violence in public houses, causing serious injuries, is very serious."