The man, aged in his early 30s, faced the Ballarat Magistrates' Court on Wednesday.

The police prosecutor told the court the man was playing for the Saints against the Sovereign Knights when the incident occurred on the night of February 10, 2020.

The court heard the Knights were in front in the last quarter and in the final minute the accused had the ball and was making a play towards the Saints' scoring end.

It was then the victim, aged 17, ran behind him in an attempt to steal the ball from behind.

The prosecutor said the accused turned and the victim made contact with his face while attempting to steal the ball, leading the referee to call a foul on the victim.

The prosecutor said the accused then struck the victim to the face or head, causing him to fall to the ground.

Witnesses described the accused moving towards the victim in a "menacing fashion", with the referee then moving between the two players.

The victim's teammates helped him to his feet as he was "unsteady and dazed", the prosecutor said, adding he was then walked to the bench.

The court was told players all provided statements that the accused's action was "unwarranted" and he was "ejected from the stadium".

The incident was reported to Basketball Victoria and the man was found guilty of a breach of conduct and suspended from playing for seven weeks.

The prosecutor said the victim, who was in year 12 at the time, saw a doctor after the incident complaining of headaches and vomiting and was absent from school for a week.

During a police interview the accused made no admissions to the offending.

After magistrate Ron Saines told the accused his sentencing would be more lenient if he pleaded guilty to save the need for a hearing and witness testimonies, the accused entered a guilty plea to the lesser charge of unlawful assault.

Defence lawyer, David Taminika, called for a conviction not to be recorded due to the possibility a conviction could result in his client losing his job.

He said his client had no prior convictions and the offending occurred in the context of sport and was not reflective of his behaviour in the community.

He submitted he had already been punished through the suspension.

"He has suffered from other players and people at the stadium making comments that he is some type of monster who should not be able to play. He attempted to [return to play] but it was so untenable that he's decided not to return to play there," he said.

Handing down his sentence, Mr Saines - who said he had played basketball for many years - said the man's "criminal reaction" on the court was not excusable.

"It is a very unsportsmanlike response. Basketball is one of the highest contact 'no contact' sports that exists because it is played at a fast pace. There are countless examples of contact with people's heads... but your response was hot headed and brought you into a criminal court.

"It was an unjustified act of violence but I will sentence you on the basis that it was not premeditated, that it was an inappropriate response in the spur of the moment."

Due to his guilty plea and being a first time offender, Mr Saines did not record a conviction but fined the man $1000, plus $85.70 in court costs.

"I hope you are able to get back to playing some sport. This is not sufficient reason to cease but to the extent that others within the sport have deemed it to be very unsportsmanlike, and I agree, but you can do a lot better in the future than what this conduct suggests."

The Courier did not include the man's name as a conviction was not recorded.

If you are seeing this message you are a loyal digital subscriber to The Courier, as we made this story available only to subscribers. Thank you very much for your support and allowing us to continue telling Ballarat's story. We appreciate your support of journalism in our great city.