Arsenal played Besiktas to a scoreless draw that saw both teams hit the woodwork and miss some other excellent chances. The biggest news coming from the match though was a leg injury for Mikel Arteta and Aaron Ramsey being sent off after picking up two yellow cards.
Bayer Leverkusen won a wild five-goal thriller against FC Copenhagen with all of the goals coming in the first half. Son Heung-Min's 42nd minute strike was the match winner as the Germans will return home for the second leg with a lead one-goal lead and a healthy advantage in away goals.
Steaua Bucuresti will take a 1-0 lead in the second leg against Ludogorets Razgrad after Alexsandru Chipciu grabbed a winner in the 88th minute. SV Salzburg will also take a lead into the second leg after they defeated Malmo 2-1.
All of Tuesday's matches are the first of two legs. Second leg matches will be played on Wednesday, Aug. 27.
Here's a recap of all five of the matches.
Besiktas 0-0 Arsenal - Full match report here
FC Copenhagen 2-3 Bayer Leverkusen
Napoli 1-1 Athletic Bilbao - Full match report here
Steaua Bucuresti 1-0 Ludogorets Razgrad
SV Salzburg 2-1 Malmo FF
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