Mikel Arteta is unsure when Pierre-Emerick Aubemeyang will return for Arsenal as the striker deals with a "personal issue".
Arsenal captain Aubameyang was withdrawn from the squad hours before their 1-0 defeat to Southampton on Saturday, which saw the FA Cup holders knocked out in the fourth round.
The Gunners play Southampton again in the Premier League on Tuesday, but Aubameyang remains a doubt.
"I don't know," said Arteta, when asked about Aubameyang's availability. "He needs to address that issue, we'll see how it evolves.
"We're here and we have to support him and he needs to take the time that is needed because that is a priority at the moment."
Arteta defends Pepe, Willian as he waits on Odegaard
Arteta revealed he was expecting an update over the weekend with Arsenal in advanced negotiations to sign Real Madrid midfielder Martin Odegaard on loan.
"Since last night I don't have any news," he said after the match on Saturday. "I will probably get a few phone calls today and see where we are with everything."
Arsenal's recruitment has come under scrutiny but Arteta defended club-record signing Nicolas Pepe and summer arrival Willian as the pair once again made little impact after coming into the team for the defeat at Southampton.
"What I am saying is they try to give their best," said Arteta. "You could see how hard they are trying, with more or less quality, but the intention is there and the willingness is there.
"This is what we demand them to do. And after the decision making, the final pass, the final goal, the opportunities they have, it is the end product and that's the hardest thing in football.
"I hope (it is only a matter of time before it starts clicking for them). We are going to keep supporting them as much as we possibly can, as a coaching staff and as a club because that is what they need.
"They need to keep working hard and try to improve their performances."
Sky Sports' Paul Merson was unimpressed by their performance and felt Arteta's decision to rotate his side, with Arsenal lying 10th in the Premier League table and seven points off the top four, was to blame.
"I don't know what he's doing," he said on Soccer Saturday.
"They are not going to win the league. They are not going to get into the top four, I wouldn't have thought, unless they go on one of the best runs in the history of the Premier League.
"For me, this is the [competition] that made Arteta last time around. He came to Arsenal and had a great semi-final and a great final."