Woden Rams player Fonua Tonga, 24, of Queanbeyan, pleaded guilty to punching a Boomanulla Raiders player twice from behind during a trial match this year.

He was charged with recklessly inflicting grievous bodily harm after the incident was referred to the police.

The victim and a Woden Rams player became involved in an altercation while playing at Northbourne Oval on March 22, with the Boomanulla player holding onto the other man's jersey.

Court documents said there had been no violence at that time and the situation had been under control.

But Tonga then allegedly punched the Boomanulla player twice from behind, with the blows landing on the man's right cheek and jaw.

The Boomanulla player was knocked to the ground where he began to bleed heavily. He was taken to hospital with a broken jaw and broken and displaced nose.

Doctors surgically inserted a metal plate and screws to fix his jaw, and screws and spacers were temporarily fixed to his upper and lower gums to prevent his mouth opening.

Tonga was sent off by the match referee and his conduct reported to the league.

Before sentencing Tonga, Justice John Burns said the victim was forced to take months off work and had become anxious and depressed.

Justice Burns said Tonga had expressed removes for his actions with several character statements noting he had become ashamed of his actions.

He said he accepted Tonga's actions were the result of a momentary loss of control although there was a need to punish his actions.

The court heard Tonga was the father of a young child and had become his family's primary source of income after his partner had a vehicle accident.

Justice Burns noted Tonga had excellent prospects for rehabilitation with no prior convictions and sentenced him to 200 hours of community service.

Tonga settled in Australia three years ago and was questioned by an Australian Border Force employee after he was sentenced.