Van Persie and United emerge from the blue mist victorious.
Sir Alex Ferguson would be the first to dismiss his side's December victory over the reigning champions as season defining. However, he would have taken great respite in knowing that they now appear to have what it takes to beat arguably the league's strongest squad over 90 minutes.
As the previous season showed, United were more than capable of going toe to toe with Manchester City over the course of a season, even opening up an eight-point advantage. But it was in the two meetings between the sides last season, when City were much the better side, that probably irked him.
This time, however, despite the last-gasp nature of the win, synonymous with United in any case, the Red Devils looked a match for the men in blue, sticking to a disciplined "sucker punch" approach that yielded two well-crafted goals.
Putting a finger on exactly how United coped better with City's attacking riches isn't straightforward. Was it in the tactics? The pre-match Ferguson sermon? Or the £24 million flying Dutchman now leading the line? Probably a combination of all three.
For all City's marauding intent—David Silva's masterful footwork, Yaya Toure's forward surges and Sergio Aguero's menacing dribbles—they were unable to match United's clinical nature in front of goal.
Striker Wayne Rooney finally spent more time facing the goal when it mattered and shared the responsibility of dropping deep with Robin van Persie, whose close control was invaluable in allowing others to join them going forward.
Of the 22 men on the pitch, one might be hard-pressed to pick a standout player, such was the involvement in the game from all areas. Though for the wrong reasons, Mario Balotelli did stand out, like a nail that is now likely to be hammered.
Roberto Mancini's faith in him is sometimes repaid, but not today, especially when it came at the cost of not starting Aguero's best strike partner, Carlos Tevez, another renegade.
It is there the problem may well again lie for City, players bigger than the club or at least the manager—a problem that Ferguson seemingly doesn't have, and never will.