Pittsburgh Steelers wide receiver DK Metcalf has been suspended for two games without pay by the NFL and will now miss the rest of the regular season after "initiating a physical confrontation" with a Detroit Lions fan during Sunday's victory at Ford Field.
The league said in a statement: "Metcalf's actions violate league policy, which specifies that 'players may not enter the stands or otherwise confront fans at any time on game day.
"If a player makes unnecessary physical contact with a fan in any way that constitutes unsportsmanlike conduct or presents crowd-control issues and/or risk of injury, he will be held accountable."
NFL Network Insider Tom Pelissero said Metcalf plans to appeal the suspension, with the 28-year-old poised to sit out the Week 17 fixture against the Cleveland Browns and then the regular-season finale against the Baltimore Ravens.
The Steelers are 9-6 and in pole position to win the AFC North, needing one win or one Ravens loss in the next two weeks.
Television footage showed Metcalf speaking to a fan, who was wearing a blue wig and hanging over the first-row railing, before throwing a punch and walking away.
The incident was not addressed during the game and Metcalf returned to play in the second half
"I heard about it, I haven't had an opportunity to talk to DK, so I have no comment," said head coach Mike Tomlin immediately after the game.
Pelissero reported on Monday that Metcalf had previously reported the same fan to Seahawks security while still playing for Seattle last season.
He added that a source informed him the fan, identified by The Detroit Free Press as Ryan Kennedy, had called Metcalf's mother a derogatory word, as well as calling Metcalf "something we both know you don't call a Black man."
Kennedy "categorically denied" allegations of using a racial slur or any other misogynistic or hate-based language in a statement released by his lawyers, Shawn Head and Sean Murphy of the Head Murphy Law Firm, on Monday.
The statement branded the accusations "completely false" and also said: "At no point before, during or after the incident did Mr. Kennedy use racial slurs or hate speech of any kind. The claims suggesting otherwise are untrue and not supported by video evidence, eyewitness accounts or any contemporaneous reporting."
Kennedy's lawyers added that their client would have no further comment because "this matter will now likely be the subject of formal legal proceedings."
Kennedy told the Detroit Free Press that Metcalf ripped his shirt during the incident and that the player was unhappy after he used his full legal name.
Metcalf, who finished the game with four catches for 42 yards, agreed a five-year, $150m contract extension with the Steelers in March after arriving in a trade from the Seattle Seahawks.
He entered the NFL with Seattle as a second-round pick out of Ole Miss in 2019 before surpassing 1,000 receiving yards in three of his six seasons with the Seahawks. He has posted 55 catches for 808 yards and six touchdowns in his first season in Pittsburgh.