Banega has not recovered from an ankle problem and did not make the squad for Saturday's La Liga game at Villarreal, Sevilla said on their website.
They did not say whether he might be available for Tuesday's Champions League Group D clash at home to Manchester City or the following weekend's La Liga match when they entertain joint leaders Real Madrid.
Sevilla made a poor start to their domestic campaign but a recent improvement, including a 5-0 hammering of visiting Getafe last weekend, has lifted them to eighth after nine games.
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In Europe's elite club competition, Sevilla won their opening match against Borussia Moenchengladbach but subsequent defeats at Juventus and City left them third in the section at the halfway stage.
Coach Unai Emery said Sevilla were relishing the challenge of taking on three strong teams in quick succession.
"It's an important week," he told a news conference after training on Friday.
"We want to be up there competing in La Liga and in Europe against top quality opponents," he added.
"But I really only want to focus on tomorrow (at Villarreal).
"It's a very tough match against a very well organised team, one of the best in the Spanish league."
(Writing by Iain Rogers, editing by Rex Gowar)
