After Forest had earned a place in the Championship playoff final courtesy of winning a penalty shootout, the majority of their fans ran onto the pitch, all but a few wanting to celebrate moving a win away from promotion to the Premier League.
However, video footage showed a supporter deliberately running head-first into Sharp, who had not taken part in the match due to injury and was on the side of the pitch.
Sheffield United boss Paul Heckingbottom revealed afterwards that Sharp, a former Forest loanee, had been left 'shaken up' and requiring stitches, while Forest quickly condemned the attack and promised a life ban once the offender had been identified.
While an investigation is ongoing, Nottinghamshire Police chief inspector Paul Hennessy said: "A 31-year-old man has been arrested on suspicion of assault in connection with this incident. He remains in custody and will be questioned by officers.
"Our enquiries into the circumstances surrounding the incident are ongoing. We have spoken to the player concerned and we are working with both clubs who are supporting us with our investigation."
Sharp spent the 2012-13 campaign on loan at Forest, scoring 10 goals in 39 games for the East Midlands side. body check tags ::