Arsenal will be without club record signing Mesut Ozil for "a minimum of three and a maximum of six weeks" with a hamstring injury, manager Arsene Wenger has announced.
The Germany international - a £42million buy from Real Madrid last summer - suffered the problem during Tuesday's 1-1 last-16 draw at Bayern Munich which saw Arsenal exit the Champions League.
Wenger confirmed Ozil would definitely be out of Sunday's north London derby with Tottenham, but was not able to put a specific time frame on recovery.
"We lose Ozil, who has been injured for Sunday, I don't know how long he will be out but it looks a minimum of three weeks," Wenger said at Friday morning's press conference.
"When the minimum is three, (then) the maximum is six. I am not specialist enough to know, it is a grade two hamstring (tear), so let's say four weeks."
Midfielder Aaron Ramsey's return from a thigh injury has been delayed, and England international Jack Wilshere is sidelined with a broken foot.
Sweden international Kim Kallstrom could be in contention for his debut after signing on loan from Spartak Moscow with a back injury while full-back Nacho Monreal is also available again.
Wenger added: "It is of course a blow, but I am confident we have the quality to deal without him (Ozil). We have many creative players who can take over to produce quality performances."