Aberdeen’s Jack MacKenzie required stitches on a head injury after being hit with an object thrown from the crowd after his side’s defeat at Dundee United.
MacKenzie, who was an unused sub, was on the pitch when both sets of fans spilled onto the pitch at the full-time whistle after Dundee United denied Aberdeen fourth place with a 2-1 win.
United boss Jim Goodwin claimed the object came from the end housing Aberdeen fans.
Speaking to BBC Scotland, Goodwin labelled the incident “a disgrace” with Aberdeen boss Jimmy Thelin telling the club’s in-house media channel that the full-back had been “badly injured”.
Goodwin said: “I deliberately took myself off the pitch as quickly as I could because we’ve had previous with the Aberdeen supporters in the past.
“I’m really disappointed to hear young Jack has been hit by an object thrown by his own supporters. He’s inside having stitches now, it’s an absolute disgrace.
“It’s probably taken something as serious as this to happen for the authorities to finally step in and do something about it to identify these idiots who let down a really good club.”
An SPFL spokesperson said: “It’s enormously disappointing and frustrating that one of the most exciting games in the season has been marred by such moronic behaviour.
“We await the match delegate report but will work closely with both clubs and Police Scotland to help identify the perpetrator and fully expect that appropriately severe footballing and judicial sanctions will be imposed.”
Sky Sports News has contacted Police Scotland and both clubs for comment.