Bukayo Saka suffered a major injury scare after being forced off for Arsenal against Crystal Palace.
The England winger was left in real pain before being replaced by Leandro Trossard after 23 minutes.
The 23-year-old was seen sitting on the Selhurst Park turf and clutching the back of his right leg.
Saka suffered a similar injury earlier in the season while playing for England in their defeat to Greece in October.
The injury eventually kept him out for over a month, missing nine games in total.
And now a new setback puts Saka in doubt for Arsenal’s clash with Ipswich Town on 27 December, with Brentford next up on New Year’s Day.
The Gunners face Brighton just three days after taking on the Bees, meaning Saka could miss multiple games.
“He put his hand up straight away,” said Sky Sports co-commentator Jamie Carragher. “I know he gets a little bit of ridicule at times for going down too much. But it looks like a problem.
“It will only be a problem for Arsenal if it’s serious. It looked like his hamstring when he tried to put a cross in and it got blocked.”
Arsenal look poised to claim all three points without their talisman though, having taken a 3-1 lead in the London derby thanks to a Gabriel Jesus double, his fourth and fifth goals this week after a hat-trick against the Eagles in the Carabao Cup, with Kai Havertz also on the scoresheet.
And Arteta’s side moved three clear in the second half after Gabriel Martinelli’s strike.