Arsenal are still yet to discover the extent of Bukayo Saka’s thigh injury but Mikel Arteta has admitted the early signs are “not good”.
The England international pulled up with the issue in the first half of the 2-2 draw at Bayern Munich on Wednesday.
Saka is set to undergo further assessment ahead of Arsenal’s home match against Everton on Saturday.
But he did not train on Friday and Arsenal face a nervous wait before discovering how long he could be sidelined for.
“He's got another MRI this afternoon because he had quite a lot of fluid in the area so it was difficult to understand the extent of the injury,” Arteta said.
"We will know more probably tomorrow. We need a few more scans and opinions from the specialists.
"Obviously when a player has to walk off the pitch and is struggling to walk without any pain and is restricted to movement, they are not good signs.
“So let's be very patient so we can give a definitive assessment, and then let you know."
Saka’s injury means Noni Madueke and Eberechi Eze will have the opportunity to start against Everton.
Madueke scored Arsenal’s winner at Nottingham Forest last Sunday while Eze was on target in the draw at the Allianz Arena in midweek.
With forward Christos Tzolis also sidelined, Madueke and Eze will be given additional responsibility for leading Arsenal’s attack.
Saka missed several stretches of the past two seasons due to a mixture of muscle injuries - dealing with hamstring, thigh and hip problems.
The 25-year-old was also affected by an Achilles injury over the final stretch of last season, which impacted his fitness at the summer’s World Cup.
Arsenal play five times before the November international break and travel to Liverpool in the Premier League next weekend.
Following Saturday’s home game against Everton, there are also trips to Fleetwood Town in the Carabao Cup and Slavia Prague in the Champions League.
They conclude the stretch of fixtures by hosting Hull in the Premier League on 7 November ahead of the two-week international window.