Both sides are in a similar position domestically, with Arsenal fifth in the Premier League and Valencia sixth in La Liga, meaning that success in the Europa League could be the best way for them to secure Champions League football next season.
The Gunners are favourites to claim a first leg win with bet365 offering a home success at 9/10 (1.90).
Valencia have lost only one of the six away matches they have played in Europe this term, a narrow 1-0 loss at Juventus in the Champions League. Los Che can be backed at 14/5 (3.80) with the draw available at 13/5 (3.60).
Arsenal look set to be able to welcome back both Mesut Ozil and Nacho Monreal from injury for the game. However, Aaron Ramsey and Dennis Suarez will be missing for the Gunners.
Valencia are without midfielder Geoffrey Kondogbia, winger Denis Cheryshev and full-back Cristiano Piccini.
Valencia's main strength this season has been their defensive solidity, with Marcelino Garcia's side having conceded the third-fewest goals in La Liga.
Arsenal have been shipping domestic goals in recent games, yet in the Europa League Emery's men have kept five consecutive clean sheets at home - including against a free-scoring Napoli side in the previous round.
The visitors will be set up to counter-attack and are unlikely to take the game to Gunners, meaning the initiative will have to be taken by the hosts.
Tips and predictions
Under 2.5 goals in the game is priced at 9/10 (1.90) and seems like a logical selection, as does opposing early goals. No goal before 29 minutes is priced at 5/6 (1.83) and should definitely be considered.
First legs of big European ties can often be cagey affairs, and even more so if the two sides boast strong defensive records. Expect neither team to come flying out of the blocks at the Emirates, which makes an early goal unlikely.
Odds correct at the time of writing. Please gamble responsibly.