The scorer wore a blue and white shirt, however, with West Brom defender Gareth McAuley inadvertently shinning the ball into his own goal after Ashley Young drove a low cross across the face of goal.
Former United goalkeeper Ben Foster tipped a Young shot onto the crossbar, but United were not able to breathe easily until substitute Robin van Persie curled a glorious shot into the top-left corner in the last minute.
City lost Samir Nasri to a first-half red card at Norwich but edged an open-ended encounter thanks in no small part to Edin Dzeko, who scored twice and might have had a hat-trick.
The Bosnian, who has had to become accustomed to a role on the substitutes' bench this season, struck twice inside the opening four minutes to put City in control at Carrow Road.
But Norwich hit back through a deflected Anthony Pilkington free-kick and the visitors were then dealt a blow when Nasri was sent off for aiming a head-butt at Sebastien Bassong.
Sergio Aguero's deft, lobbed finish restored City's two-goal cushion in the 50th minute and although Russell Martin headed in for Norwich, Dzeko made it 4-2.