Arsenal manager Arsene Wenger fears Francis Coquelin could face a spell on the sidelines due to a hamstring injury.
The midfielder picked up the problem in his side's 3-3 draw with Bournemouth on Tuesday and was forced off after just 28 minutes, making way for Alex Oxlade-Chamberlain.
Coquelin will undergo a scan in the coming days to determine the extent of the injury, but Wenger expects bad news after seeing the player's reaction on the pitch.
"Coquelin has a hamstring problem," Wenger told reporters.
"It is too early, you have to wait 48 hours for a scan to see. But usually when he sits down and comes up it is not so good news.
"If it is just a tightness, the player tries to get on but he did not even try to play again."
Olivier Giroud netted a stoppage-time equaliser to salvage a draw for Arsenal after previously scoring a wonder goal in the 2-0 win over Crystal Palace on Sunday and Wenger was full of praise for the striker following his crucial effort.
"Every player is important. I said on Sunday that Giroud can score important goals and he has done that again," Wenger added.
"When you play in the box he is dangerous. Giroud again scored because we dominated and he can score a header."