Laurent Koscielny is unavailable due to a three-game suspension after being sent off in the 3-1 success over the Toffees, while summer signing Shkodran Mustafi is a doubt having not trained since missing the win at The Emirates Stadium.
The Germany international was absent due to illness and remains worse for wear just three days before the final.
Club captain Per Mertesacker made his first Arsenal appearance of the season against Everton and could be enlisted again to cover the desperate injury plight.
Twenty-one-year-old Rob Holding is likely to be retained in a back three which could see Nacho Monreal moved into a central position. Alex Oxlade-Chamberlain is fit again after missing the last three games with a hamstring injury.
"Gabriel is out for 6-8 weeks," said a downbeat Arsenal manager Arsene Wenger at a press conference to preview the game, according to The Mirror. "We had a scare about his cruciate but it's medial. He avoids surgery. Alexis Sanchez is ok; Oxlade-Chamberlain is in contention for final. Mustafi is still sick and hasn't trained yet."
Sanchez, Arsenal's top scorer this season with 29, limped off after 68 minutes against Everton, raising fears the Chile international may be the victim of another fitness concern. But Wenger is confident the forward will be fit for the game given his remarkable powers of recovery.
"He [Sanchez] needs to go through some tests at the moment," added Wenger. "We'll see how well he comes out of that. Knowing his player, knowing his commitment to the club, he'll do everything to be fit for Saturday."