David De Gea 8 - continues to star this season. Made a number of fine saves, even though he looked like he was playing through injury.
Paddy McNair 7 - started again, and in all four games that he's started, United have won. He was solid and steady in a big game, and Louis van Gaal must be delighted.
Chris Smalling 8 - recovered from the recent criticism to put in an excellent performance. Made blocks, tackles, clearances, won aerial battles - more of the same is needed.
Tyler Blackett 6 - not quite as steady as usual and committed a few errors, but none were too harmful to the United backline.
Antonio Valencia 7 - was effective at right wing back, and drove in the cross for the opening goal in an efficient display out of position.
Luke Shaw 6 - struggled to cope with Alex Oxlade-Chamberlain before being substituted with an injury after just 16 minutes.
Michael Carrick 7 - steady and efficient in possession, which United needed with Daley Blind out. Proved he can still do it in the big games.
Marouane Fellaini 7 - looks to have gained confidence since returning to the side, used the ball well and wasn't afraid to get stuck in.
Angel Di Maria 6 - blew hot and cold. Dangerous when running one minute, but making odd decisions before wasting a glorious chance to make it 3-0.
Wayne Rooney 7 - continues his great run of form with another goal. A real purple patch for the United captain, who scored the winner with a superb chip over Damian Martinez.
Robin van Persie 5 - whilst he usually impresses against his former club Arsenal, tonight he was virtually anonymous - a recurring theme for the Dutchman this season.
Ashley Young 7 - much like Valencia, he fared well in an unfamiliar role, and could stay there if Shaw's injury is serious.
James Wilson 6 - didn't really do much other than pressure the Arsenal backline and hack the ball to safety from wide areas.
Darren Fletcher - came on for Young with just one minute to play, and didn't have a huge impact with such little time left.