Arsenal scored two first half goals to put one foot in the Europa League Semi-Finals – but it is far from over even with a two goal lead.Goals from Aaron Ramsey and Lucas Torreira gave the Gunners a deserved buffer for the second leg in Naples next week, as the Serie A side crumpled under some severe first half pressure.Boss Unai Emery went with an attacking lineup, naming both his star strikers, Lacazette and Aubameyang, in the eleven, with Mesut Ozil operating just behind. Width came in the form of wing-backs Ainsley Maitland-Niles and Sead Kolasinac, and Aaron Ramsey partnered the combative Lucas Torreira in the centre of the park.That meant a three man defence in the form of the returning Laurent Koscielny, Sokratis and Nacho Monreal, with Petr Cech taking the gloves. The emphasis was certainly on attack, perhaps with the knowledge that the Stadio San Paolo is a vociferous one and with our away form being sketchy, taking a lead to Italy was a must.So we got to work early.We earned a series of corners to show our intent, and our movement, so slack against Everton in the weekend, was revived.Napoli have often relied on star man Kalidou Koulibaly and he came to the rescue early on with crucial blocks on shots from Ramsey and Maitland-Niles. The Gunners were clearly in the mood, and the Italian side were on the ropes, unable to cope with the movement.Koulibaly was helpless minutes later though, as a flowing move culminated in the opener.Maitland-Niles, Lacazette and Ozil were all involved in some slick passing and the ball was worked artfully to Ramsey who was lurking in the box and his first time finish was lashed home.Success, and we had the goal our start deserved.We weren’t finished though.A counter was sparked by Kolasinac winning the ball and finding Ramsey, who combined with Lacazette. The Frenchman found Kolasinac, who had continued his run, and a trademark pull-back from the Bosnian just missed Laca, and was cut out before Aubameyang could strike.On the 25th minute, we had a vital second.This was again started thanks to our hunger to win the ball back, Torreira this time was the man who grabbed possession back. He won it high up and carried on, before using his footwork to deceive a defender. It worked space and he aimed for the corner, but that man Koulibaly was on hand to block once again. The ball took a wicked deflection and wrong-footed the keeper, and it was 2-0.We retained possession thereafter, but the foot was lifted from the gas pedal a little. We had to wait until the 40th minute for our next big chance, and keeper Alex Meret performed a miracle to first save from Aubameyang, and then grab the loose ball before Lacazette could snaffle the chance up.It wouldn’t be Arsenal without some drama though, and just before half time, Napoli should have had a goal, as Callejon passed to Insigne, who blasted over.It was a let off.The second half was a more balanced affair with chances for both sides, but with the second leg left finely balanced, what can we take away from this performance?Koscielny Must PlayThe Skipper returned from injury, and his experience counted for much. With Napoli coming into the game in the second forty five, Koscielny marshalled the backline well and his chemistry with both Sokratis and Monreal was the reason why we go to Italy with a clean sheet.We Have Missed TorreiraIf we are to keep it tight in Naples, then our Uruguayan is vital. Our away form is woeful, but a defensive presence helps enormously. Torreira gives us that, and his recent suspension correlated with some iffy performances. He also gives us options to name a three-man midfield if we want to slow down Napoli. In short, Torreira will give us a fighting shout in Italy.Maitland-Niles For The WinWhat a find our youngster is. He continuously bombed forward and then covered at the back. His stamina, his positioning belies his years and he played a big role in our opener. He will continue to improve but we can thank our lucky stars that with Bellerin out for the season, we have a more than capable stand-in.Goals Throughout the SideWhen you have the likes of Auba and Laca in your side, it is easy to rely on them for goals. Both played decent in this game, but neither rippled the net. Instead, it was our central midfielders who took the mantle and bagged the goals we needed, and it is really encouraging that when our strikers fail to register a goal, we have others to step up and be counted. A good omen.We had chances in the second half to put this tie to bed, but poor finishing and some great keeping by Alex Meret denied us the third goal we needed. On the other hand though, Napoli tested Cech a few times and we kept them out.A two goal lead taken to Italy is good news, but will we come to regret those missed chances?We’ll find out next week.