Paul Mitchell has been jailed for 14 weeks after assaulting Aston Villa midfielder Jack Grealish during Sunday's derby.
Mitchell was wrestled off the playing surface by stewards after punching Grealish around the head in the ninth minute of Sunday's Birmingham derby.
Pub worker Mitchell also admitted a charge of invading the pitch after magistrates rejected an application for his address to be withheld.
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Prosecutor Jonathan Purser told the court that Mr Grealish felt lasting pain after the incident but had suffered no substantial injury from a punch to the right side of his jaw.
He went on to score the winning goal for Aston Villa in the 67th minute.
In a statement read into the court record by Mr Purser, the Aston Villa captain said: "I cannot help but feel how lucky I was in this incident.
"It could have so much worse had the supporter had some sort of weapon."
Jack Grealish celebrates at full time after scoring the winning goal.
Mitchell's solicitor Vaughn Whistance told the court: "He cannot explain what came over him yesterday morning. His initial foolish intention was to just go onto the pitch and whip up the crowd."
Earlier, Mitchell's lawyer said his family had had to leave their home due to threats following his arrest after the "high-profile" incident.
Making an application for the court to withhold Mitchell's home address, Mr Whistance, told the court: "There have been various comments posted on different social media
"My client's young family have had to leave their home address to move to outside of Birmingham through fear that they would suffer serious harm or even death."