Kai Havertz is currently being assessed over a knee injury
The German was absent from Arsenal's open training session put on for the fans at the Emirates Stadium on Wednesday.
Havertz has only just returned from a long-term hamstring injury which kept him out between February and May.
The club are assessing the situation and are waiting for the injury to settle before further analysis.
Analysis: Injury issues strike again for Arsenal
Just days ago, the topic of debate was which striker out of Havertz or Viktor Gyokeres should start in Arsenal's big game against Liverpool next week. "I think Mikel Arteta will go back to Havertz in the big games," said Jamie Carragher. "I would be very surprised if Havertz doesn't play."
Now it seems that the decision has been taken out of Arteta's hands.
No matter the severity of this Havertz knee injury, the German will be a major doubt for the trip to Anfield - placing a huge focus on Gyokeres in the first big game of his Arsenal career.
But once again, Arsenal are talking about injuries after it derailed them last season. Havertz, Gabriel Jesus and Bukayo Saka all missed over a dozen league matches due to injury last term - only the latter is fully fit at the start of this one.
Arsenal do know that Mikel Merino can fill in as an emergency option but that was an awkward scenario last season which Arteta and the Arsenal team made the most of. Playing the Spaniard as a No 9 again is a situation they want to avoid, if possible.
What this situation does tell us, though, is that Arsenal will have to get Gyokeres on song soon, after a slightly underwhelming Premier League debut at Manchester United last weekend.
Saturday's game against Leeds - which Gyokeres will almost certainly start now - is important in the early context of Arsenal's season. Goals are needed.
A huge run for Arsenal: their next six fixtures
August 23: Leeds (H), Premier League, kick-off 5.30pm, live on Sky Sports
August 31: Liverpool (A), Premier League, kick-off 4.30pm, live on Sky Spotrs
September 13: Nottingham Forest (H), Premier League, kick-off 12.30pm
September 16-18: First Champions League fixture
September 21: Manchester City (H), Premier League, kick-off 4.30pm, live on Sky Sports
September 28: Newcastle (A), Premier League, kick-off 4.30pm, live on Sky Sports
This season, Sky Sports' Premier League coverage will increase from 128 matches to at least 215 games exclusively live.
And 80 per cent of all televised Premier League games this season will be on Sky Sports.
