Arsenal's Kai Havertz has undergone a minor surgical procedure on his knee, but his absence is not expected to be as lengthy as initially feared, the club said in a statement on Thursday.
Havertz played the final 30 minutes of Arsenal's 1-0 win at Manchester United on the Premier League's opening weekend but missed last Saturday's 5-0 thrashing of Leeds United.
- Arsenal's Champions League draw: Bayern, Inter, Atlético, more
- Norway call up Ødegaard to ease injury concerns
- PL overreactions: Arsenal or Chelsea to win PL
Gunners boss Mikel Arteta was coy over the extent of the injury when speaking to media, but it has since been confirmed he will require an operation after returning to his native Germany for further tests.
A statement from Arsenal read: "Further to sustaining a knee injury after our recent game against Manchester United on 17 August, subsequent assessments and specialist reviews with Kai confirmed that surgery would be required.
"Today, Kai underwent a successful minor surgical procedure. He will shortly begin his recovery and rehabilitation programme, with everyone fully focused on supporting Kai to ensure he is back to full fitness as soon as possible."
The expectation is that Havertz's absence will be measured in weeks rather than months if all goes to plan and is not considered a long-term problem.
However, it does heighten the pressure on Viktor Gyökeres as the club's €73 million ($85m) summer signing from Sporting Lisbon is their only fit recognised striker heading into Sunday's trip to Liverpool.
Havertz's injury accelerated Arsenal's move to sign Eberechi Eze from Crystal Palace for an initial fee of £60 million.
Eze was presented to the Emirates crowd prior to Arsenal's victory against Leeds and is primed to make his debut against Liverpool at Anfield on Sunday.
As well as being without Havertz for the trip to face the Premier League champions, Arteta is also unable to call on Bukayo Saka and Martin Odegaard after they sustained hamstring and ankle injuries, respectively, against Leeds.
Christian Norgaard and Ben White are also injury doubts, while Gabriel Jesus remains a long-term absentee with a knee injury.
Information from PA was used in this report.