Arsenal will be without Alexandre Lacazette for four to six weeks due to injury - leaving Danny Welbeck as their only available senior striker in the Europa League.
The club confirmed their £52 million summer signing has undergone an arthroscopy on his left knee in London on Tuesday morning.
January purchase Pierre-Emerick Aubameyang is ineligible to play Europa League football for Arsenal because he was registered in former club Borussia Dortmund's squad for the knockout stages.
Arsenal said: "The minor procedure was a success and he will now undergo a period of rehabilitation.
"It is envisaged that he will return to the squad within four to six weeks."
The tournament could represent Arsenal's best chance of qualifying for the Champions League with Arsene Wenger's side eight points behind fourth in the Premier League.
The London club face an away tie against Swedish side Ostersunds on Thursday in the last-32 of the competition.
