Sergio Aguero was involved in an altercation with a fan as unsavoury scenes marred the aftermath of Wigan Athletic's stunning 1-0 FA Cup win over Manchester City.
Will Grigg scored the only goal of the game after 79 minutes to book a quarter-final tie against Southampton for Paul Cook's League One promotion-chasers and end the runaway Premier League leaders' prospects of a historic quadruple.
A significant number of home supporters invaded the pitch to celebrate when the full-time whistle sounded at the DW Stadium and television pictures showed a Wigan fan approaching Aguero from behind, appearing to say something to the Argentina striker, who swung round a right arm and struck the man.
Wigan defender Chey Dunkley helped to defuse the situation, with Aguero visibly angry.
Meanwhile, some of the travelling City support were involved in an altercation with stewards, during which objects – including an advertising hording – were thrown as some Wigan followers goaded their opposite numbers.
Reacting to the events, Wigan chairman David Sharpe told BBC Radio 5Live: "It is not nice to see, football is emotional, it is what it does to fans. But I don't like to see this at the end of the game.
"It is a massive result, but we have to stay classy in football. I don't like what I am seeing here."
Earlier, tempers threatened to boil over between both sets of players and their coaching staff when City left-back Fabian Delph was sent off for a rash lunge on Max Power in first-half stoppage time – a challenge that will rule the England international out of Sunday's EFL Cup final against Arsenal.
Referee Anthony Taylor had a yellow card in his hand initially, with the dismissal serving to rile Delph's team-mates and provoke furious reaction from Pep Guardiola on the touchline.
However, Guardiola's opposite number Paul Cook played down the flashpoint.
"There's no problems," the Wigan boss told BBC Sport. "From our point of view we're trying to get every edge and everything we can, and from his point of view he wants the game played and he's a fantastic manager."
|Harden should be MVP ´hands down´, says World Peace|
|Southgate optimistic over Alli recovery for Belgium decider|
|Neymar´s tears no surprise to Fagner|
|Unhappy Renard continues ref rant|
|Wallace takes BMW International title despite Olesen 61|
|Hamilton cruises back to standings summit with France win|
|In-form Kvitova defends Birmingham title|
|Southgate responds to toughest England week in record-breaking style|
|Uruguay not thinking about Portugal or Spain, insists Cavani|
|Coric stuns Federer to claim title in Halle|
|England 6 Panama 1: Kane hat-trick sees Southgate´s side sail through|
|Australia v Peru: Juric keeping the faith as Socceroos chase unlikely last-16 spot|
|England surpass class of 1966 in Panama rout|
|Nigeria v Argentina: All eyes on Messi to rescue final World Cup chance|
|NSW seal Origin series with comeback win|
|World Cup 2018: Stalin´s bunker, a space museum and Serbian specials in Samara|
|Croatia looking out for number one - Lovren|
|Heritage at back of Australian minds ahead of potential Croatia encounter|
|It may be my last World Cup - ´Realistic´ Pogba determined to reign in Russia|
|Lionel Messi´s birthday: What might the Barcelona star wish for?|
|Russia readying Dzagoev for last-16 clash|
|Germany apologised for reaction aimed at Sweden bench|
|Picture this! Sterling starts for England against Panama|
|World Cup 2018: A Russian romp, Maradona and the party in Moscow|
|Happy birthday, Lionel Messi! 10 of the Argentina star´s best goals|
|Modric worthy of Ballon d´Or, says Lovren|
|Sigurdsson ready for Croatia reunion as Iceland go for broke|
|Iceland v Croatia: Dalic to rest stars for Hallgrimsson divorce hearing|
|Men´s tennis will have to ´wake up´ after Federer and Nadal, says King|
|Tennis star Djokovic backs VAR despite Serbia controversy|
|Socceroos have deserved more at World Cup – Skoko|
|Dodgers top Mets in Kershaw´s return from DL|
|MLS Review: Red Bulls end Dallas´ unbeaten run, Sporting stage comeback|
|Hierro: This Spain team similar to 2010 World Cup champions|
|Dowrich, Holder lead Windies fightback after poor start|
|With Neymar back, Brazil are World Cup favourites – Lugano|
|Alba: I don´t understand the criticism of Messi|
|He has sacrificed a lot – Stuani praises Suarez|
|Manning says Brees deserves to break his record for career passing yards|
|Hornets want Walker to play entire career with Charlotte|
|Avalanche sign Grubauer to three-year extension|
|Argentina struggles down to team, not just Messi – Hierro|
|Casey leads Travelers by four after firing 62|
|Scotland run riot in Argentina as Hourcade tenure ends in defeat|
|Germany´s Rudy in doubt for South Korea clash|
|England produce storming fightback to beat New Zealand|
|Shaqiri, Xhaka facing disciplinary action over goal celebration|
|Kvitova takes WTA lead for wins by easing into Birmingham final|
|Jones: England back on road to being world´s best|
|Germany survive in Sochi but questions remain|
|Germany 2 Sweden 1: Late Kroos winner brings Low´s men back from the brink|
|Perisic dreaming of matching Croatia´s France 98 heroes|
|Veron questions Sampaoli for leaving Icardi out|
|Southgate won´t blame injured Alli for playing through pain barrier|
|Travelers Championship: Course invader drives Rory McIlroy and crowd nuts|
|Saul tells Atletico to renew Oblak deal after Griezmann´s new contract|
|Course invader sends McIlroy & crowd nuts at Travelers Championship|
|Saudi Arabia v Egypt: El Hadary eyes history in dead rubber|
|Referee declines Cheika invite after Australia´s series loss to Ireland|
|Griezmann, Mbappe can eclipse Henry, claims Trezeguet|
|Nawalka hopeful of Glik return against Colombia|
|Mexico outsmart South Korea to join Croatia as unheralded World Cup threats|
|´No drama´ for Southgate after England team sheet leak|
|Hend caught by five in Pulheim as Bjerregaard goes low|
|´Little Pea´ Hernandez hits big Mexico milestone in World Cup win|
|Modric and Rakitic the best midfield in Russia - Corluka|
|Cipriani and Farrell ease pressure on Jones as England avoid SA whitewash|
|South Korea 1 Mexico 2: Hernandez nets landmark goal as last 16 beckons|
|Ozil and Khedira axed by Germany|
|Djokovic plans to use two rackets against Cilic after reaching Queen´s final|