Alexandre Lacazette scored the only goal in Naples on Thursday to seal a 3-0 aggregate victory for Unai Emery’s side and secure their place in the semi-finals for the second year in a row where they will face Valencia.
It was a comfortable evening in the end for Arsenal at the Stadio San Paolo, with the only negative being a suspected hamstring injury suffered by midfielder Aaron Ramsey during the first half.
Back in the Premier League, the Gunners currently occupy the final Champions League qualification position with five games remaining. Emery’s side
Koscielny was full of praise for the professionalism of his side’s performance in Italy but urged his teammates to move on quickly and start preparing for the weekend.
"We came here with ambition and wanted to win and score some goals. We did it with Laca,” Koscielny told BT Sport. “We kept a clean sheet, which is important for the confidence. Each game we have in front of us is a final. Tomorrow we switch back to the Premier League.
"We know Napoli played in the Champions League this season. They are a good team. We did the job at home. Today we knew if we scored they needed four. We fight to defend and suffer together."
Gunners boss Emery, a three-time winner of the competition with Sevilla, expressed his delight at his team’s performance in his 50th game in charge of the club.
"I am proud of the players,” he told BT Sport. “We started very well. The first half was good because after we scored we continued not to give them opportunities. We defended well second half. In the two matches, we can be happy to win against Napoli."
On Arsenal’s semi-final opponents Valencia, Emery added: "They are a very good team with goods players. It will be a difficult match for us."