Arsenal and Besiktas played out to an entertaining 0-0 draw in their UEFA Champions League qualifier at the Olympic Stadium.
Arsene Wenger will be without midfielder Aaron Ramsey for the second leg, after he was shown a red card in the second half.
Demba Ba nearly opened the scoring with the first kick of the game, as he spotted Szczesny off his line but his effort from the halfway line was palmed away the the Arsenal number one.
Ba came close again in the ninth minute, but his left-footed was parried away by Szczesny.
The Gunners registered their meaningful shot in the 35th minute, as Jack Wilshere found some space on the edge area before curling straight at Zengin.
Olcay Şahan should have given the the home side the lead minutes after the restart, but the striker curled his effort wide of the upright from 12-yards out.
The visitors were dealt a blow in the 80th minute, as Ramsey was shown his second yellow card of the game for tug on Oğuzhan Özyakup.
However, Wenger's men almost won it in the 88th minute, Alex Oxlade-Chamberlain danced through Besiktas defence before rifling an effort onto the frame of the goal.
Tuesday night's other results:
Napoli 1-1 Athletic Bilbao
Red Bull Salzburg 1-1 Malmo
FC Copenhagen 2-3 Bayer Leverkusen
Steaua Bucuresti 1-0 Ludogorets