The Gunners have a healthy lead but inconsistency and opponents buoyed by a big weekend win means this tie isn't over.
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- Arsenal recovered to win 3-1 in last week's first leg
- Hosts have won last eight at home in Europa League
- Unai Emery was coach of Valencia from 2008–2012
- Marcelino: "We are convinced we can do it"
- Winners v Chelsea/Frankfurt in final on 29 May
Reporter's view: Valencia's experiment with a new formation didn't go to plan in London. Expect Marcelino to return to his favoured 4-4-2 set-up, which he deployed in the 6-2 weekend win at Huesca. Arsenal will face a much more robust Valencia. Mestalla is a daunting place, and while the Gunners' lead makes them slight favourites, a fightback and either extra time or a famous victory isn't out of the question.
Graham Hunter, Valencia reporter
Valencia: Neto; Piccini, Gabriel, Diakhaby, Gayà; Soler, Parejo, Wass, Guedes; Mina, Rodrigo
Out: Cheryshev (knee), Kondogbia (thigh)
Arsenal: Leno; Mustafi, Papastathopoulos, Koscielny; Maitland-Niles, Guendouzi, Xhaka, Kolasinač; Iwobi, Mkhitaryan; Lacazette
Out: Bellerín (knee), Holding (knee), Ramsey (hamstring), Welbeck (ankle)
Gonçalo Guedes v Laurent Koscielny: Arsenal's defence has been much criticised, but after a shaky start to last week's first leg, it proved sufficiently solid to keep Marcelino's side at arm's length in the second half. The experienced Koscielny was absolutely vital in this effort and will again need to be at his best to deal with the clever runs of Guedes. Portugal's Guedes had a relatively quiet first leg but is Valencia's potential game-changer.
Andy Brassell, Arsenal reporter
Where to watch
Marcelino, Valencia coach
Undoubtedly we have a better chance of progress if the Mestalla is behind us from the start. We will have difficult spells but we go into the game full of the conviction that we can win.
We need a 2-0 win. I want us to play with intelligence and patience, to attack and be daring. We also have to defend very well. We are dealing with top-level players who have already shown us that they can take advantage of any carelessness.
Unai Emery, Arsenal manager
For us it's the same message as the first leg: we are 50/50, the first-leg result does not change my viewpoint. Tomorrow is going to be very difficult.
Our idea is to play the match thinking to win. To win you need to score. They are an organised team, strong defensively but they need to score. They have attacking players with big quality.