Amateur footballer jailed over on-field coward punch during a game

A footballer has been jailed after he coward punched another player, breaking the man's jaw, during a game in Adelaide's south.

Mark Harrison, 34, has been sentenced to one year and 10 months' jail before Adelaide District Court over the punch, which occurred back in September 2018 during the B-Grade grand final between Christies Beach and Flagstaff Hill in the Southern Football League.

During the game, Christies Beach player Harrison struck an opponent, causing the Flagstaff Hill player to fall to the ground unconscious with a broken jaw.

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Flagstaff Hill former president Brett Charlesworth has told 9News the punch was a cowardly move, which significantly affected the victim.

"He suffered a very, very nasty injury," Mr Charlesworth said.

"It affected him in many ways... He's bounced back from it but it's something that he'll carry for the rest of his life."

The former football club president said Harrison being jailed over the punch was "a really important step forward" in discouraging violence on the field.

"The more we can do to stamp out this sort of behaviour, the better," he said.

Lawyer Greg Griffin has also praised the custodial punishment handed to Harrison.

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"It sends a really strong message to anyone that plays social suburban sport that you cannot assault people on the sporting field," he said.

"And if you do, you put your reputation, livelihood and even freedom at risk.

"One stupid act on a football field is a life-changing event for you and you can go from having everything that you want in life to having that taken away."

Harrison had a history of one-punch attacks and was on a good behaviour bond at the time of the incident.

He was sentenced to a non-parole period of 11 months.

He could also now face a lifetime ban from the football league, with the matter to go before its board.