Aberdeen defender Jack MacKenzie was left bloodied after being struck by what seemed to be a seat – thrown by one of his own fans – amid a pitch invasion following his side’s Scottish Premiership defeat at Dundee United.

Unused subtitute MacKenzie was on the pitch while the United supporters invaded the playing surface after their side denied Aberdeen fourth place.

And he was felled by a projectile hurled from the area of the ground that housed a travelling support restricted in number after objects were aimed at United manager Jim Goodwin in the last meeting at Tannadice.

Aberdeen manager Jimmy Thelin told BBC Scotland after the match MacKenzie is “ok but it’s quite a bad injury.”

“This is unacceptable and can’t happen,” Thelin added.

“We have to get all the facts of what actually happened. All we know is Jack got a really bad injury as a player doing his job. This cannot happen in this way.”