There was mass confusion just after the hour mark when the referee pointed to the penalty spot after Blackett, on for Brady a few minutes earlier, tumbled inside his own box under a clumsy challenge from an AmaZulu forward. Sense prevailed after United's protestations, however, and the Reds escaped unscathed.
Petrucci rattled the crossbar from distance in the game's closing stages before Kagawa's eventual inclusion on 89 minutes earned the biggest cheer of the night.
As pre-season openers go, Sir Alex will consider this a success. He successfully juggled youth with experience to hand 17 players time on the pitch, gave new signings their first United minutes and, most importantly, none of his men sustained serious injury. No wonder he, along with more than 50,000 people, left the Moses Mabhida stadium smiling.
United: Lindegaard; Veseli (Vermijl 46), Wootton, Ferdinand, Brady (Blackett 58); Carrick, Scholes (Tunnicliffe 70), Lingard (Petrucci 70); Hernandez (Kagawa 89), Berbatov, Macheda (Anderson 58).