Former United striker Danny Welbeck had given impressive Brighton a first half lead but Rashford pulled United level when he expertly slotted home a sharp pass from Bruno Fernandes
Greenwood sealed the victory on 83 minutes when he headed home from close range.
Brighton were fuming however as they were denied a penalty as the scores were locked at 1-1. Harry Maguire appeared to have held back Welbeck but VAR and referee Mike Dean thought otherwise.
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Brighton were fuming however as they were denied a penalty as the scores were locked at 1-1. Harry Maguire appeared to have held back Welbeck but VAR and referee Mike Dean thought otherwise.