1. United's high defensive line

In the very first minute, Walcott got clear of Rojo which showed United's shakiness. The United backline wasn't very composed and there was evidence of lack of communication in the first 5 minutes, as Blind and Carrick took turns and moved much higher up the pitch to press, leaving a gaping hole at the back. This was highlighted by a one-two played between Welbeck and Alexis which saw the latter enter the box but with no success. The next and probably best Arsenal chance again originated from Blind pushing higher up and Carrick holding his ground as Monreal ghosted in behind to latch on to Ozil's dink, De Gea was up for the task though. The marking was poor as nobody tracked Monreal's run as Varela, Carrick and Blind were equally at fault. Man United looked jittery.

After a dominant first 10 odd minutes, the Arsenal midfield started to lose shape as both Ramsey and Coquelin seemed to be out of sync. With both players not covering enough ground after a set piece, Marcus Rashford found himself in acres of space before being fouled just outside the box. This led to a pattern as Arsenal would surrender possession in or outside the final third and United would pounce with the bright Rashford leading attacks and running at the defence. The space he found himself in underlined the lack of midfield presence for the Gunners, something they would soon be punished for.

Nacho Monreal has been the best left back in the league this season, head and shoulders above his peers but on this occasion, he not only found himself out of depth but also out of help. Alexis Sanchez, one to always hustle and buzz across the pitch barely provided him any assistance, on more than one occasion, going in field and pressing instead of holding his position thus causing numerous 2 on 1s against the Spanish fullback and it was no surprise that both of United's first 2 goals came from that wing. While Koscielny and Gabriel could be accused of not clearing their lines when having the opportunity to do so, the left side of the defence was just tactically undermanned. Walcott lost the ball to start with inside his own half and Alexis was caught way infield. The pattern followed for the second goal as well, just 3 minutes later. At least, this time, Alexis made his way to the box but was caught chasing shadows as Lingard fired in a pinpoint centre for Rashford to head in. The movement of Lingard and Varela was barely tracked and neither Koscielny nor Gabriel read the cross, as the young Rashford wheeled away in celebration a second time.

Man United seemed to take their foot off the gas after establishing a 2 goal lead and their tempo fell as the half drew to a close. A simple free kick without much angle from Mesut Ozil found Welbeck's head, which in turn found the back of the net. Arsenal had found themselves a lifeline from nowhere but it was more due to United losing their composure at the back-Rojo made no attempt to clear, despite marking Welbeck-than Arsenal being prudent in attack. United had collected a number of silly fouls before the one that led to the goal, and their energies were seemingly down as Arsenal ended the half strongly with a couple of free kicks and corners to cap off a poor half.

(Monreal chasing shadows before the third goal)