The Gunners will travel to Turkey to square off against a Fenerbahce side that is as stocked with quality as embroiled in controversy. The runners-up in last season's Super Lig are only being allowed to play in qualifiers until their appeal of a match-fixing decision can be heard.
Arsenal, of course, cannot count on the Turks being ruled on legal grounds and must summon the might within their comically threadbare squad to emerge from the first leg in a favorable position to qualify.
Here are four key battles that fans should pay attention to.
Even before the Premier League opener last weekend, Arsenal's squad was in an utterly shambolic state. According to Arsenal.com, five key first-teamers are nursing significant injuries that were sustained before the team played Aston Villa.
Then, in an archetypal case of Murphy's Law, Kieran Gibbs, Tomas Rosicky, Aaron Ramsey and Bacary Sagna all picked up knocks, while Alex Oxlade-Chamberlain appears to be set for a lengthy spell on the sidelines.
Fortunately, James Olley is reporting that Arsenal have caught a major break, as the former three will probably be fit to play. If he is incorrect, however, Arsene Wenger might find it difficult to field a lineup composed entirely of senior players.
Arsenal will meet an old foe again when Dirk Kuyt, who made over 200 League appearances for Liverpool, steps onto the pitch against an English side he knows well.
As one of only three players in Fenerbahce's team with Premier League experience, Kuyt is already acquainted with the more physically robust English style of play and may even be able to recall previous meetings with some of Arsenal's players.
If the gash on Kieran Gibbs' head manages to seal up in enough time to allow him to resume his role as left-back, the Gunners will probably feel somewhat secure.
However, if Carl Jenkinson, or, depending on injuries, someone else fills the void, there will be significant cause for concern with a wily veteran on the right wing.
With Arsenal's total lack of attacking firepower, wringing the utmost out of their few resources is absolutely vital.
Much of that task falls to the feet of Olivier Giroud, the club's only true striker. Arsene Wenger might have burdened the club with shallowness through profligacy and frugality, but Giroud is healthy and firing, and his potency is crucial to maintaining that of Arsenal's attack.
His chief obstacle will be Nigerian center-back Joseph Yobo, who accrued considerable Premier League experience during a decade with Everton and is still a physical man-mountain at the age of 32.
If Yobo manages to stifle Giroud, Arsenal will find it very difficult to puncture Fenerbahce's back line.
It is worth noting that, even if Fenerbahce defeat Arsenal over two legs and progress to the group stage of the Champions League, they could be barred from competing if the Court of Arbitration for Sport denies their appeal a day later.
After club officials allegedly fixed matches to help Fener claim the 2011 League title, the Turks were suspended from the next two UEFA club competitions they qualify for.
This would obviously be one of them. It's not clear whether Arsenal would automatically progress if Fenerbahce's suspension is upheld, or if Salzburg, who were beaten by the alleged cheaters in the previous round, would get another crack at qualification.
Either way, it's a situation that Arsenal desperately wish to avoid and should not have to confront.