The Red Devils have had problems with their penalty kick takers this season and they struggled again at Carrow Road.
Marcus Rashford missed from the spot before United changed their spot-kick taker to Anthony Martial, who then also failed to beat Tim Krul.
Scott McTominay gave Manchester United the lead in the 21st minute, sweeping in from a corner after Krul had saved well from Anthony Martial.
United were handed the opportunity to double their advantage from the penalty spot after a VAR review ruled Ben Godfrey had fouled Daniel James.
Rashford‘s spot-kick was saved by the Dutchman but the England international atoned moments later by slotting past the Norwich keeper to make it 2-0.
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