Hector Bellerin, Nacho Monreal and Alexandre Lacazette ruled of Arsenal clash against Milan
Pierre-Emerick Aubameyang is also ineligible for the contest at the San Siro.
Arsenal trio Hector Bellerin, Nacho Monreal and Alexandre Lacazette will miss Thursday's [8 March] Europa League clash with AC Milan though injury.
Bellerin, 22, was dropped from the Gunners starting XI last Sunday [4 March] as his side crashed to a 2-1 defeat to Brighton and Hove Albion but any hopes of returning to the fold for the visit to the San Siro have been dashed by a knee injury.
Arsene Wenger is confident the issue will not rule out the Spaniard in the long-term but with the full-back spending Wednesday [7 March] in hospital, the manager will be taking no risks for the first leg of their last 16 clash with Gennaro Gattuso's side.
"He is injured - he has an inflammation of his left knee, without ligament damage," Wenger told the club's official website. "He had a scan yesterday, which was quite good. It showed inflammation.
"He tried [to train] today but he needs some further investigation. He was in hospital this afternoon to know why he is in so much pain. But it doesn't look a long-term problem. He tried, he went out but couldn't absorb the training session so we had to leave him behind."
Monreal has not featured since limping out of the Carabao Cup final against Manchester City. Lacazette meanwhile underwent surgery in early February to address a knee issue, and while Wenger has recently spoke of the France international returning ahead of schedule, that will not be in time for their clash with the Rossoneri.
"Apart from that, of course Lacazette is not ready and we had to leave Monreal behind because he is not ready," Wenger continued. "He started a little session today only, but he is not ready."
Arsenal's club record signing Pierre-Emerick Aubameyang will also be unavailable as he is ineligible for the competition.