A teenager accused of bashing an autistic boy alongside two spanner-wielding friends was "antagonised" on Instagram before the fight, a Melbourne court has been told.
The 15-year-old, who is on bail, is likely to avoid a criminal conviction if he is deemed suitable for a diversion program to take his matter out of the court system.
The teen, who cannot be named for legal reasons, appeared in a children's court on Tuesday supported by his mother and sister.
It is claimed he was messaged on Instagram by his 14-year-old victim before the alleged incident outside Northcote High School on May 8.
The victim wanted to fight over an alleged bullying matter regarding a friend, police said.
The teen tried to ignore the messages at first but then turned up to meet his victim alongside two other boys, aged 14 and 15, it is further alleged.
One of the others pushed the victim off his bike and punched his face before he was then assaulted with what appeared to be spanners, police said.
The victim was taken by ambulance to hospital for a suspected head injury, cuts and bruises.
A few days later, the teen was interviewed by police, allegedly claiming he didn't want to fight "but I knew it was going to happen".
"In his immaturity, (he) did take matters into his own hands," the teen's lawyer said on Tuesday.
"It has culminated in this pretty ugly fight.
"My client didn't start this fight. He went there to talk but he knew quite quickly it wasn't going to be a talk."
The teen has since been expelled from his school, the court was told.
He will return to court later on Tuesday to determine if he is suitable for a diversion program.