Darren Bent's injury-time penalty condemned Manchester City to their first defeat of the season - 1-0 at the Stadium of Light as a glaring miss left Carlos Tevez red-faced.
The Sunderland striker converted the spot-kick in the fourth minute of added time to snatch all three points after being hauled down by Micah Richards in front of goal.
Bent's strike was the Black Cats' reward for a concerted second-half fightback after Tevez had let them off the hook with an astonishing early miss.
The Argentinian fired high over an open goal after being played in by Yaya Toure, and the visitors were made to pay as the points slipped away.
Roberto Mancini's side dominated before the break, but were unable to take advantage, and the home side made the most of their opportunity despite losing striker Fraizer Campbell with what looked like a serious injury.
That brought greater urgency to Steve Bruce's pursuit of Ghana international striker Asamoah Gyan ahead of the transfer deadline, although he was able to comfort himself with a spirited display by his team.
The drama came right at the death and when referee Mike Dean pointed to the spot after Richards had prevented Bent from reaching Elmohamady's cross, the striker made no mistake as City conceded for the first time this season.