The 21-year old scored twice - in the 73rd and 83rd minutes - as the Black Cats came from behind to lead after Fernandinho's 2nd-minute opener before conceding late to Samir Nasri.
Wickham believed that Sunderland, sitting bottom of the table, deserved to beat third-placed City but suggested the performance would act as a catalyst for their final five fixtures as they strive for survival in England's top flight.
"We created chances in the game against such a good team," he told Sky Sports.
"To concede early wasn't ideal but we pulled ourselves back and I do think we were unlucky to not take three points."
Wickham, who took his Premier League goals tally to three, added: "It's one of the most difficult places to come in the Premiership against such a good team.
"We conceded early but pulled ourselves back into the match and then to see the ball roll into the back of the net was agonising.
"The boys are feeling it inside but we can take positives from today and take it into Saturday (against Chelsea)."
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