Mavropanos, 20, signed for Arsenal in January of this year from Greek side PAS Giannina but has mostly been used by the U23 side.
However with a crucial Europa League semi-final second leg to come against Atletico Madrid on Thursday, Wenger has rotated the team despite being away against old foe Jose Mourinho. That means Mavropanos starts at centre-back next to Calum Chambers.
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Ainsley Maitland-Niles starts in the centre of midfield whilst Reiss Nelson partners Pierre-Emerick Aubameyang, who cannot play in the Europa League, and Henrikh Mkhitaryan, who plays against his former side, in attack.
For Manchester United Victor Lindelof comes in to replace Phil Jones whilst former Arsenal forward Alexis Sanchez starts.
TEAMS IN FULL
Manchester United - De Gea, Valencia, Smalling, Lindelof, Young; Matic, Pogba, Herrera; Lingard, Sanchez, Lukaku. Subs: Pereira, Rojo, Fellaini, Mata, McTominay, Martial, Rashford
Arsenal - Ospina; Bellerin, Chambers, Mavropanos, Kolasinac; Xhaka, Maitland-Niles; Iwobi, Nelson, Mkhitayran; Aubameyang. Subs: Cech, Holding, Monreal, Osei-Tutu, Willock, Welbeck, Nketiah
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