Dzeko is just not used to the pace of the English game yet, the most overused cliche for new players in the Prem, but imo that really is the case this time. His technical ability is ok, he just needs to understand that he doesn't have as much time on the ball.
As for Vidic, i thought he was MOM today. He ate Tevez for breakfast, i never thought he'd make marking a player like Tevez look so easy. He was never beaten in the air, and he just got in City's face all game long. He was quite average at the start of the season when Rio was missing, but that looks like it was because he was playing alongside the calamity Evans

. That being said, Smalling was very good as well. Makes me boil seeing him playing games like today's one, seeing as we were in the race to sign him alongside United.
On another note, i'm loving this new rejuvenated RVP, deadly in front of goal, and is such a joy to watch. I just hopes he stays fit, he really is a top class player when he keeps himself fit for an extended period of time.