Arsene Wenger acknowledged he is facing mounting midfield problems as Arsenal enter a decisive stage in the campaign.
French midfielder Mathieu Flamini will be suspended for at least three matches, ruling him out of Sunday's meeting with Crystal Palace and the clashes against Liverpool and Manchester United, after collecting a red card in the 2-2 draw at Southampton on Tuesday.
And the Arsenal manager revealed Aaron Ramsey has suffered a set-back in his recovery from a thigh problem that forced the Wales midfielder to miss the trip to St Mary's Stadium.
The draw meant Arsenal missed out on the chance to move four points clear at the top of the Premier League table and could head into the next round of fixtures in third place if Manchester City beat Tottenham on Wednesday and Chelsea secure a two-goal margin of victory over West Ham on the same day.
Ramsey is expected to at least miss the visit of Palace and Wenger said: "He is out for longer than expected because he had a little set-back in training on Tuesday so I couldn't bring him here.
"It's the same muscle, but faded again. So we have to be cautious when we bring him back."
Wenger agreed the loss of the two players would stretch his midfield resources, but he refused to condemn Flamini, who was dismissed in the 80th minute for a two-footed challenge on Morgan Schneiderlin.
"Look we have to see it again, to me it looked harsh. He got the ball," Wenger said.
"At some stage we all have all the feet off the ground. If you say every time a guy makes two-footed tackle its red, he deserved a red.
"If you say it was a violent tackle, I would say no. I don't know, the referee made the decision and we have to cope with it."
Arsenal were forced to come back after falling behind to Jose Fonte's 21st minute header, taking the lead with goals from Olivier Giroud and Santi Cazorla within seven minutes of the restart.
Adam Lallana quickly equalised for Southampton but Wenger insisted this was a valuable point gained.
"I wouldn't say it was a very bad performance," he said. "It was a very good football game. Southampton deserve credit.
"I don't complain about the quality of our game. We went down to 10 men and we at least went home with a point.
"You want three points in every game. But Southampton is a difficult place to come to and when you look overall it can happen you can get only one point away from home."
Mauricio Pochettino, the Southampton manager, praised his team's display.
"I thought the team was outstanding. I thought we played sensational football," he said.
"The second half we didn't start too well, conceded two goals, but we showed great character to get back level so quickly."
Like Wenger, Pochettino insisted he didn't get a clear view of the sending off.
"It's hard to say from my position on the pitch. But Flamini's sending off didn't affect the outcome of the game," he said.
"It didn't change what Arsenal deserved to get out of the game and it didn't affect what we should have got from the game."