The first shot on target was a tame one, 10 minutes later, with Michael Carrick's harmless daisy-cutter rolling through to Bunn, and it was only around the half-hour mark that the Reds started to click into gear. To their credit, the Canaries defended manfully as Rooney saw shots blocked by Michael Turner and Russell Martin but the East Anglians looked comfortable without showing too much ambition themselves.
When van Persie worked the ball onto his favoured left foot, expectations were high but the leading scorer skied a wayward effort into the Stretford End and the frustration continued until first-half injury time to compensate for an earlier knock to Bunn.
Chris Smalling fed Antonio Valencia and the winger's low cross was nudged on the stretch by van Persie into the path of Kagawa, who tucked the ball past Bunn with the outside of his right foot. There was concern for van Persie, as he appeared to hurt himself when supplying the assist, and then Patrice Evra after the latest of Robert Snodgrass' lunging tackles saw him rightly booked.
Norwich started the second half with more intent and Vidic was forced to clear behind his own goal when Snodgrass tried to meet a cross by Anthony Pilkington. Although Bunn had to be out to prevent Rooney latching onto an astute through ball by Kagawa, City continued to press with Jonny Howson's drive deflecting wide off Carrick.