Arsenal's Jack Wilshere has had a "minor procedure to stop ankle discomfort", says boss Arsene Wenger.
The midfielder, 23, has not played since hurting his ankle in his side's 2-1 defeat by Manchester United in November.
He first had surgery in November and was on the bench for last Saturday's win at Crystal Palace.
Wilshere has now had two pins removed from the joint but Wenger said he would be missing for "days, not weeks".
Midfielder Mikel Arteta (ankle) and defender Mathieu Debuchy (shoulder) are still a few weeks away from returning.
'I am hurting' - Wenger
The Gunners go into Sunday's Premier League match against Everton following a 3-1 first-leg defeat in the Champions League at home to Monaco.
Wenger was left annoyed at another poor knockout showing in Europe's top club competition and wants a positive reaction from his players.
"What is hurting is the defeat more than the criticism," said Wenger. "I do not say I am immune to it. I love to win and when I don't win, I am hurt of course.
"We fought very hard against Besiktas to qualify [in August]. What is frustrating is that we've gone out in the last 16 in the last four years.
"There is nobody to blame individually. On the night everything went against us and missing chances was only one characteristic."
Wenger 'expects a strong response'
Arsenal, currently third in the table, remain on course to qualify for the Champions League for an 18th straight season, but are 12 points behind leaders Chelsea.
"I expect a strong response because it's a different competition," said the Frenchman. "We have an opportunity to maintain our top-three position.
"You play 55 games a year and you have moments where you are disappointed. We want to finish the season in a strong way."