Ole Gunnar Solskjaer's side ended its 11-match run without a win away from Old Trafford by beating Partizan Belgrade in the Europa League in midweek, and backed it up with an impressive performance at Carrow Road.
United broke the deadlock through Scott McTominay's low drive and in the process became the first club to score 2,000 Premier League goals. The visitors were then awarded a penalty after a VAR review in the 28th minute, only for Krul to save Rashford's effort, but the England international made up for it moments later to get his 50th United goal.
Solskjaer's side missed its second penalty before halftime when Martial was denied as Krul again guessed correctly to keep his side in the game. It was 3-0 in the 73rd as Martial made up for his penalty miss before Norwich pulled one back in the 88th through halftime substitute Onel Hernandez, who became the first Cuban goalscorer in Premier League history.
VAR was used for the first time in the 28th when Ben Godfrey was adjudged to have brought down Daniel James in the box after a lengthy review, only for Rashford to be denied by Krul. But just two minutes later Rashford made amends for his second missed penalty of the season as he beat the poor Norwich offside trap to collect James' pass and slotted home.
For the second time in the first half, the visitors were awarded a penalty after another VAR review, this time for a handball by Todd Cantwell in the area. Martial stepped up to take the spot kick, but Krul made a diving save low to his right to deny the United forward.
United wrapped up all three points in the 73rd as Rashford and Martial linked up with a clever one-two before the French forward - in his first Premier League appearance since August - slotted home his third league goal of the season.
Just as the game looked to be petering out the Canaries pulled one back, with Hernandez hitting his first goal of the season after a solo run.
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