Arsenal striker Alexandre Lacazette will be sidelined until October with an ankle injury.
The 28-year-old had been playing through the pain, but has now been told to rest the problem.
A statement on Arsenal's website said: "After assessments to an ongoing ankle issue, we have advised that Alex will need to rest and strengthen his ankle to regain full fitness.
"Alex has been playing through this injury for several weeks. He is likely to be back in action in October."
Lacazette has scored two goals in three appearances this season, the last of which came in the 2-2 draw with Tottenham, when the Frenchman was replaced in the 67th minute.