Two goals from Aaron Ramsey and Torreira ensured Arsenal had an upper hand in their first leg tie against Napoli.
Arsenal kicked off in high spirits making accurate passes that paid off in the 15th minute when Aaron Ramsey finished a Maitland-Niles pass sending it into the back of Napoli’s net.
Ten minutes later Uruguayan Torreira fantastic control of the ball deflected off the body of Napoli defender Koulibaly doubling the lead.
Napoli fell short of Arsenal in terms of passing as they lost most of the possession in the first half.
In the second half, Napoli regained possession as Arsenal looked relaxed as they wasted many clear chances.
Napoli had two clear chances of scoring when Insigne’s efforts failed to convert into a goal. Koulibaly’s header in the second half was also tapped off by Czech who kept a clean sheet for the Gunners.
Elsewhere, Chelsea score a solitary goal against Slavia Prague giving them an away goal advantage in the Europa League.
With four minutes left to the end of the normal 90 minutes, Alonso converted a Willian ball into the back of Slavia Prague net.
In other Europa League fixtures, Benfica gunned down ten-man Eintracht Frankfurt of Germany beating them 4-2 at home. Valencia stunned fellow Spanish club Villarreal beating them 1-3 at their home soil.