Upon the evening that the provisional English squad was announced for the upcoming international friendlies, there's was a lot of pressure hoist upon Danny Welbeck. The Englishman, who hasn't seen a lot of play time down to being down the pecking order or injured, was included in Gareth Southgate's selection.As is always the case with a player who has not been seeing much game time, his inclusion was met with confusion; why not include someone in-form like Brighton's Glenn Murray? What has Welbeck done in recent weeks to warrant an inclusion?This was all before Thursday night's kick-off against AC Milan in the second leg of the Europa League last 16 fixture, which Arsenal currently led 2-0 after a fine performance in the San Siro last week. Due to the injury of Alexandre Lacazette and his counterpart Pierre Emerick Aubameyang being cup-tied for the fixture, it was former Manchester United man Welbeck who would be leading the line against the Rossoneri, and the pressure was very much on him to perform.Thankfully, for his sake, he did and bagged a brace on the night to send the Gunners on their way to the quarter finals.It wasn't all plain sailing though. After Hakan Calhanoglu put Genarro Gattuso's side 1-0 up with a long range blast early on in the first half, the crowd - which was admittedly lighter than usual - must have been fearing the worst. Coming from behind is not a forté of Arsenal's of late, and nightmares from the Ostersund performance at the Emirates must have been haunting Wenger.Thankfully, luck was on Arsenal's side. And it really was luck, because the first goal was very questionable and its acquisition has dominated much of the post-match conversation. Welbeck made his way in to the Milan penalty area, and when he was just within it, he took to the ground after what appeared to be a touch by left-back Ricardo Rodriguez. The Swiss defender certainly didn't make much impact on Arsenal’s forward - if any - put a few seconds later, the referees whistle sounded: penalty to Arsenal.Milan was furious and perhaps rightly so. The word dive has been bandied around following the game, with Wenger even admitting he would have a "talk" with his player if it were the case. Regardless, Welbeck picked himself up and took the penalty, which he slotted by Gianluigi Donarumma in the Milan goal to make it all even at half time and 3-1 on aggregate.It must have truly deflated Gattuso's side. One goal to nil at half time and playing well - his side were still very much in the game. But Welbeck's controversial goal flipped the tie on it's head, and in the second half, Wenger's side built upon their advantage in a way that was good to see.Going in to the game there were plenty of defensive doubts - Shkrodan Mustafi, Nacho Monreal and Hector Bellerin were all subjected to late fitness tests, with all three being deemed fit enough to feature from the start. In fact, it was the fourth defender of a back four that had to leave the field injured - Laurent Koscielny leaving the field with a back injury early on to be replaced by Calum Chambers. The back four held firm throughout, along with goalkeeper David Ospina. Ahead of them, and perhaps the stand out performer on the night, was Granit Xhaka, who not only put in an excellent performance, but was the second player in an Arsenal shirt to find the net on the night with his 71st minute finish, which effectively put the tie to bed. His effort - which was typical for the Swiss midfielder in that it was outside the area - did not look like it would trouble Milan's young Italian keeper, but his luck was not in on the night and he fumbled before allowing the ball to hit the net. 2-1 on the night, 4-1 on aggregate and it looked like the tie was settled.There was still time for Welbeck to add his second of the night though, this time in less controversial circumstances. He was quick to react to Donarumma's parry of an Aaron Ramsey header, and showed the clinical nature that he has shown so many times in the past, if not as of-late. Hopefully the two goals will add to the English striker's confidence, although with Lacazette back training, there will be more depth up front for the next tie.And that was that. The full time whistle went an Arsenal were 3-1 winners and into the quarter final stage of the Europa League. Milan were understandably disappointed by the awarding of the penalty, but ultimately, Arsenal were the better team on the night and earned their victory. It was another good performance, and with the upcoming international break, Wenger and his side have the longest break they've had in months to regroup and prepare for the next round and the league run-in.The last 8 teams in the competition have now taken shape, and there have been some shock exits. Last night Red bull Salzburg became the first Austrian team to ever reach this stage of the competition after claiming the scalps of German giants Borussia Dortmund. They are joined in the last eight by Arsenal, Lazio, Red Bull Leipzeig, Marseille, CSKA Moscow, Sporting Lisbon and tournament favourites, Atletico Madrid. There are plenty of strong teams left in the competition, but after beating AC Milan, there is nobody that Arsenal should be fearful of going into this stage of the competition. The Europa League is likely Arsenal's best opportunity of making it to the Champions League next season and potentially Wenger's last chance for glory, so supporters will wait with bated breath for the next round in what has become a very interesting competition.