Sheffield United striker Billy Sharp was attacked by a pitch invader as they suffered a penalty shoot-out defeat to Nottingham Forest in the Championship play-off semi-finals.
Steve Cooper's Forest sealed a penalty shoot-out victory to progress into the final where they will face Huddersfield Town for a place in the Premier League.
The Blades won the game 2-1 on the night to take the tie to extra-time, but were denied by three penalty saves from Forest keeper Brice Samba.
Despite a thrilling affair, it was soured by the attack on the 36-year-old, who was stood watching Forest celebrate.
Sky Sports video captured a man run full speed at Sharp before smashing him to the floor.
It has since been confirmed that Sharp was treated at the City Ground and received stitches.
Sheffield United manager Paul Heckingbottom was left furious by incident and made it known in his post-match interview.
Heckingbottom said: 'We're seeing things thrown on the pitch and things that are thrown on putting players' health and safety in danger and nothing's ever done about it.
'There will be something done about that. We've seen what's happened, we know what's happened. There's a prison sentence there without a doubt.
'How can you come to a place of work minding your own business and be assaulted in that fashion?
'It's just bang out of order and it's everything that's wrong. Too many times we hear people condemn it, but nothing's done about it. We're the ones that suffered.
'It's upsetting for a lot of reasons - I don't want to say too much more about it. He'll be dealt with.'