Arsenal midfielder Mathieu Flamini has been ruled out of action for three weeks with an ankle injury.
The 24-year-old limped off before half-time during the Champions League defeat to Liverpool on Tuesday.
Brazilian Gilberto will replace the Frenchman for Sunday's crucial Premier League showdown with leaders Manchester United at Old Trafford.
"It is a big blow but Gilberto has a lot of quality and experience," Wenger told the club's official website.
"Gilberto can come in and help the team recover and focus."
Arsenal are third in the table, six points behind Manchester United, and need to win on Sunday to stay in the title race.
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