Arsenal manager Unai Emery said Aaron Ramsey may be out for "some weeks" after he suffered an apparent hamstring injury in Thursday's Europa League quarterfinal win over Napoli.
The timeframe could mean the Wales international, who is bound for Juventus in the summer, has played his last match in a Gunners jersey.
"It is a muscular injury. Normally it will be some weeks out for him," Emery told BT Sport after Arsenal's 1-0 victory at Napoli.
Ramsey exited the match in the 34th minute, shortly before Alexandre Lacazette curled his free kick for the game's only goal.
When asked at a postmatch news conference if Ramsey's season is over, Emery said: "I don't know."
The win ensures that Arsenal have at least two more matches in Europa League play, with an upcoming semifinals series with Valencia, as well as five more matches in the Premier League.
If Arsenal beat Emery's former side to reach the Europa League final, they'll play either Chelsea or Eintracht Frankfurt on May 29.