Manchester United

David de Gea 8 Breathtaking saves from Cazorla and Sánchez kept United in the game and was assured as ever. Did not deserve to be on the losing side

Antonio Valencia 4 Caught hopelessly out of position for Monreal’s goal and awful back-pass gifted Welbeck the winner. One of his poorer games

Chris Smalling 5 Poor touch allowed Sánchez an opening and missed a glorious chance to score from inside the six-yard box and keep United in the Cup

Marcos Rojo 5 Rash at times and fortunate the referee missed a grab on Welbeck’s shoulder when the striker was through. Yellow carded then taken off

Luke Shaw 6 Struggled to cope with Oxlade-Chamberlain’s direct running but got forward when he could until his number came up

Ander Herrera 5 One delightful ball to Di María showed what he can do but remains on the periphery of the play and was hauled off at half-time

Daley Blind 6 Kept United ticking over in the Carrick role until the man himself came on but United’s midfield lacks the necessary forward thrust

Ángel di María 7 Wonderful cross for Rooney’s goal, forced smart save from Szczesny and drilled a shot wide before he was sent off for grabbing the referee

Ashley Young 7 Ran at Bellerín at every opportunity, forcing Wenger to substitute the Spaniard, but never managed to break the shackles completely

Marouane Fellaini 7 His presence and hold-up play gave Van Gaal’s side a threat, if not a pretty one. Passed up great chance to shoot to show his limitations

Wayne Rooney 8 Restored to favoured striker role he took his goal with aplomb. Looked sharp on the turn and was quick to switch attacks but lacked support

Arsenal

Wojciech Szczesny 6 Saved well from Di María at his near post but looked shaky at times and almost patted a searching cross straight into Fellaini’s path

Héctor Bellerín 6 Early booking for tackle on Young made it a testing night and could easily have got a second yellow before he was substituted

Per Mertesacker 7 Started nervously on return to the side but thwarted dangerous Di María raid early in the second half and made vital interception late on

Laurent Koscielny 7 Left Rooney too much space for the goal but grew in stature as the game went on and dealt with United’s front two without panic

Nacho Monreal 8 Defensive discipline has made him Wenger’s No1 left-back but showed great composure with his goal. An unlikely hero

Francis Coquelin 8 Early blow to his broken nose didn’t stifle his energy. Buzzed around Fellaini to win second balls and start Arsenal attacks

Santi Cazorla 7 Began slowly but his quick feet had a greater effect in the second period and his fine strike was only denied by a world-class De Gea save

Alex Oxlade-Chamberlain 8 Tore at the United defence from the off and showed wonderful footwork to create Monreal’s goal. Injury ended his game not long after the break

Mesut Özil 6 A typical day at the office for the German. Clever and threatening every now and again but not involved enough for the money

Danny Welbeck 7 Surprise selection ahead of Giroud and heavy first touches suggested rustiness but was quick to pounce when it mattered most

Alexis Sánchez 7 Tricky and direct, his battle with Valencia was a feature. Not his best performance in an Arsenal shirt but never tired and nearly got his goal