Police are investigating an alleged assault on Nottingham Forest player Kelvin Wilson after a fan ran onto the pitch at the end of a match, BBC reports.
A 23-year-old Derby County fan was initially arrested on suspicion of pitch encroachment but has since been bailed after being interviewed about the incident.
The man broke through the line of pitch-side stewards following Forest's last minute victory over Derby at the iPro Stadium on Saturday.
He appeared to swing an arm at Wilson before his teammate Jamaal Lascelles and stewards intervened.
A clip posted on video sharing website Vine captured the moment following the match.
Superintendent Gary Parkin said: "A 23-year-old Derby supporter from the south stand entered the playing area and made contact with a Nottingham Forest player. The supporter has been arrested and a joint investigation will be taking place between Derbyshire Police and Derby County."
Derby County could also face an investigation by the Football Association following the incident.
Following the game, Forest owner Fawaz Al Hasawi also claimed his car had been vandalised in the director's car park. Police are investigating the damage.