Manchester City's quadruple trophy bid was sensationally derailed by a shocking 1-0 defeat at third-division Wigan in the FA Cup fifth round on Monday.
With the Premier League leaders down to 10 men after Fabian Delph's red card, Will Grigg scored a stunning, breakaway goal in the 79th minute as Wigan beat City for the third straight time in the FA Cup, after their 2013 final and 2014 quarterfinal victories.
The main talking point came on the stroke of half-time as City's Fabian Delph was controversially sent off for sliding in on Max Power.
An irate Pep Guardiola became embroiled in a touchline argument with Wigan boss Paul Cook, and the managers continued their row in the tunnel as the teams left the field at half-time; they had to be separated by colleagues.
After the game, City striker Sergio Aguero appeared to be involved in an altercation with a fan as the celebratory pitch invasion at the DW Stadium turned ugly.
Yet, despite their numerical disadvantage, City had only themselves to blame for spurning a host of chances against the League One side, who now go forward to a quarterfinal clash with Southampton, against all odds.
It was only City's third defeat in all competitions this season, following the Champions League loss to Shaktar Donetsk on Dec. 6 and their lone Premier League setback against Liverpool on Jan. 14.
They will now turn their attention to winning those two competitions, as well as the Carabao Cup, in which they will face Arsenal in the final on Sunday.
Adding to Guardiola's frustration might have been bad tackles on Sergio Aguero and Danilo by Dan Burn and Gavin Massey respectively, but his team also lacked a cutting edge.
They dominated possession throughout but could not take advantage. Aguero headed over early on, and Ilkay Gundogan forced a good save from Christian Walton.
Gundogan found himself in another good position only to mis-kick, and Aymeric Laporte also failed to make clean contact in front of goal. Fernandinho blazed over from a gilt-edged opportunity about 8 yards, Gundogan missed the target with another effort, and Danilo dragged a shot wide.
Yet all the while, Wigan were defending stoically and threatened occasionally on the break.
Claudio Bravo needed to be alert to smother the ball at Gary Roberts' feet, and Grigg fired into the side netting after beating John Stones. Aguero looked like he would open the scoring after breaking into the box just before the interval, but Walton produced another fine save.
Controversy then erupted as referee Anthony Taylor dismissed Delph following a sliding challenge on Power. Taylor initially had a yellow card in his hand but eventually brandished the red one, sparking vociferous complaints from City players, who felt the decision was harsh.
Guardiola was also angered and encroached onto the field, his arguments with Cook continuing for some time afterward.
People appeared to calm down during the break, and City, minus Delph, soon reasserted their dominance. Again they controlled much of the ball, but Wigan continued to defend stubbornly, and Guardiola sent Kevin De Bruyne on after the hour in the hope of opening them up.
Yet the frustration continued for City, with Fernandinho having a shot blocked and nobody able to turn in a Danilo ball across goal. Grigg capitalised on a Kyle Walker error to win it for Wigan late on with his seventh goal of the FA Cup campaign, which leads the competition.
The Northern Ireland international seized possession on halfway and charged upfield before slotting a fine shot past Bravo from the edge of the area.
Wigan survived a nervy finish, with the final whistle prompting a pitch invasion.