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.