Arsenal must beat Besiktas to earn a place in the Champions League group stage, "no matter what it costs", says manager Arsene Wenger.
The Gunners, who have reached the group stage for the last 16 seasons, travel to Turkey for Tuesday's first leg, with the home leg on Wednesday, 27 August.
"We're desperate to go through. We want to play in the Champions League we know how big these games are," said Wenger.
Arsenal defenders Laurent Koscielny and Kieran Gibbs face fitness tests.
That could mean an earlier than expected recall for Per Mertesacker, who returned late for pre-season training after helping Germany to World Cup success.
Wenger confirmed: "It was our plan to bring the Germans back in contention for Everton [on Saturday], but in case of emergency I will take Mertesacker.
"It is a bit early for him. Ideally we would need one more week preparation, but he is willing to play, no problem."
Arsenal beat Crystal Palace 2-1 in their opening Premier League game of the season on Saturday before flying out to Istanbul.
They will face Slaven Bilic's side at the 72,000-capacity Ataturk Olympic Stadium, where Liverpool beat AC Milan in the 2005 Champions League final, as Besiktas's Vodafone Arena is being redeveloped.
Besiktas, runners-up in last season's Turkish championship defeated Dutch side Feyenoord 5-2 on aggregate in the third round of qualifying, with former Chelsea striker Demba Ba scoring a hat-trick in the second leg.
Arsenal defeated another Turkish club, Fenerbahce, at the same stage last season.