After Sheffield United Captain Billy Sharp was assaulted by a fan during the second leg of their Championship play-off semi-final at Nottingham Forest, police detained a guy.

As Sharp remained on the sidelines during a pitch invasion, a television video showed a fan charging at him.

Forest triumphed 3-2 on penalties after a 3-3 deadlock in the first two matches.

“One foolish idiot spoiled what was an amazing night of football,” Sharp, 36, added.

“Congratulations to Nottingham Forest on their victory and good luck in the final,” he wrote on Twitter.

“As a former Forest player, I will not allow one jerk to tarnish my admiration for Forest supporters.”

“I’m incredibly happy to captain this set of Sheffield United players; they gave it their best and deserve to be proud.”

Sharp required sutures, according to Blades boss Paul Heckingbottom, while Forest were “appalled.”

After the match at Forest’s City Ground, Heckingbottom said, “We’ve seen one of our players attacked.”

“Bill was minding his own business off the pitch, trying to get our players away. He’s rattled up, bleeding, and angry.”

“It was cowardly of him to be blindsided. He was knocked to the ground and needed sutures, as well as being shaken.”

The Football Association stated: “We are aware of the terrible incident that occurred following Nottingham Forest’s match against Sheffield United.”

“We will conduct an urgent investigation into the issue and will collaborate with the clubs and necessary authorities to ensure that the proper procedures are taken.”

Following the event, Nottinghamshire police initiated an investigation.

“A 31-year-old male has been arrested on suspicion of assault in connection with this incident,” Nottinghamshire Police Chief Inspector Paul Hennessy said.

“Officers will question him while he is still in detention. Our investigation into the incident’s circumstances is still ongoing. We’ve spoken with the player in question, and we’re working with both teams to help us with our inquiry.”

Sharp played on loan with Forest in the 2012-13 season but was unable to play due to injury.

Forest said the offending fan would be banned for life in a statement.

“Nottingham Forest Football Club is outraged to read that our former player, Billy Sharp, was assaulted following tonight’s match at The City Ground,” they added.

“The club would also want to apologize to Billy personally and to Sheffield United Football Club,” said the statement.

“The club will collaborate with the authorities to discover the individual in order for them to be held accountable for their crimes, which will include a life ban from Nottingham Forest.”

“How can you come to your place of employment and mind your own business and be abused in that fashion?” Heckingbottom said after the game.

It’s completely out of sequence, and everything is wrong.” People decry it far too often, but nothing is done, and we are the ones who suffer. It is sad for a variety of reasons, but it will be addressed.”

Former Forest defender termed it an “utter disgrace.”

The UK’s football policing chief told in January that arrests at football events in the top five English leagues were at an all-time high, with fan disorder “growing worse.”