Arsenal manager Arsene Wenger says Laurent Koscielny has a swollen face problem and will be assessed tomorrow ahead of the mid-week Champions League game against Paris Saint-Germain.
The Frenchman suffered the injury in the last part of the game against Southampton.
The Gunners registered a hard-fought win to move up to fifth in the table with the defender as well as Santi Cazorla both on target.
"Look, we had a little bit of a slow start and after 20 minutes we were 1-0 down, so we came back well into the game and we had a good response," Wenger said.
"In the second half I felt we dominated well again and created many dangerous situations but couldn't score. Because we threw everything forward we were always a little bit under threat on the counter-attack of Southampton and in the end we got the penalty, so it's a relief.
"When you lose your first home game, you cannot afford to drop points in the second home game because it creates a little bit of anxiety at home and that's not what we really want.
"It is a win after Watford, that is two wins together. If we can put a few wins together, of course that will help us to be more confident and to get to a very fluent level like we want to play.
"I haven't seen it [the penalty] again on video. They tell me in the dressing room it was a penalty, 100 per cent penalty.
"Have you seen it again on video? I haven't. There were maybe one or two on corners before, I don't know. But I'll watch it again, I promise you. It's difficult for me to give you an opinion.
"[Laurent] Koscielny has a problem with his face. He's with the doctor now. I haven't spoken to him yet, but it is very swollen."