Pep Guardiola was involved in a furious row with Wigan boss Paul Cook as Manchester City's quadruple bid was sensationally derailed by their FA Cup bogey team.
Will Grigg scored a stunning late breakaway goal as Wigan repeated their shock 2013 final victory over City in a fiery fifth-round tie at the DW Stadium, winning 1-0.
The main talking point came on the stroke of half-time as City's Fabian Delph was controversially sent off and an irate Guardiola became embroiled in a touchline argument with Cook.
The pair continued their row in the tunnel as the teams left the field at half-time and they had to be separated by colleagues.
After all Guardiola's recent complaints about bad tackles on his players, Delph was dismissed for sliding in on Max Power.
Yet, despite their numerical disadvantage, City only had themselves to blame for spurning a host of chances against the League One side.
Grigg made them pay in the 79th minute as Latics secured another famous victory over City following their 2013 success and another in the quarter-finals the following year.
Against the odds, it is now they who go forward to a last-eight tie with Southampton and not the runaway Premier League leaders.
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 eight 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 opening 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 on to the field, his arguments with Cook continuing for some time afterwards.
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. 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.