Mikel Arteta admitted Bukayo Saka's injury "doesn't look good", pointing to the packed calendar as a potential reason.
Arsenal came from behind to earn a late 2-2 draw with Bayern Munich, with Declan Rice scoring an 82nd-minute equaliser.
Eberechi Eze, Saka's replacement, had given the Gunners the lead before Harry Kane set up Alphonso Davies to level the score and then put Bayern in front from the penalty spot.
This was only the second time Arsenal have scored first, fallen behind, but then avoided defeat in a European Cup/Champions League match, and the other was also a 2-2 draw with Bayern in April 2024.
Despite the positive result, it was marred by Saka's exit in the 10th minute after he pulled up while trying to play a routine pass, and Arteta sounded pessimistic about the injury.
"They [the medical team] are a bit concerned," Arteta told TNT Sports.
"A player who has to come off with a really sharp pain is never good news, but we have to wait and see."
Asked in his press conference if the hectic schedule played its part, Arteta added: "Against Lille, he didn't start the game. Then he started the game at the weekend. And then it's very early in this game.
"The level of intensity these games require is something incredible. You could see what happened in the PSG-Barcelona game [on Tuesday]. This is man-to-man for 96 minutes. Every action. There's no breathing.
"The strength, the quality, the attention, the level that you need is unbelievable because it's the highest level.
"Those things happen, unfortunately. It doesn't look good at all, but we have to wait and see."
No Premier League side has had more goal contributions from substitutes in all competitions this season than Arsenal (five goals, four assists), with Eze scoring and Viktor Gyokeres assisting off the bench against Bayern.
But it was one of their starters, Rice, who had the decisive say as he netted his sixth Champions League goal, though this was his first away from home.
He has also been involved in five goals in his last eight games in all competitions (one goal, four assists).
"When you play against teams who are man-to-man all over the pitch, you have to apply certain principles," Rice told TNT Sports.
"They follow you all over the pitch, but I lost my man, and I just kept running and lost my runner, and then I was in on the goal. So happy. Gyokeres has been making such a good impact coming off the bench. He made some great runs and set me up for the goal.
"It is what the manager has drilled into us. We aren't just going to come here and sit. At home, they are probably one of the best teams in Europe, so to come here and give that account of ourselves was really good. We have to keep going."
jewbdimprs
1
Hope Saka recovers quickly
hohbdelprs
1
Let Dowman come in now
Expensive597
0
Always blame Great Man City for every issue RED CARTEL face
You want to bring your FFP ass into this? 😆 🤣 😂
Expensive597
0
who's to follow saka as soon as possible
your team captain
luodenoty
0
who's to follow saka as soon as possible
DeoDarius
1
I don't pray for his injuries, wish him quick recovery.. but i was hoping for eze to get more games for his confidence and settling boost, he needs it
wusbmnrsz
2
Always blame Great Man City for every issue RED CARTEL face
wusbmnrsz
2
All Great Man City FAULT [Crylaugh][Crylaugh][Crylaugh]
wusbmnrsz
0
It's Great Man City FAULT [Crylaugh][Crylaugh][Crylaugh]
wusbmnrsz
2
Saka is injured cause Great Man City cheated [Crylaugh][Crylaugh][Crylaugh]