Arsenal will assess Alexis Sanchez's hamstring injury before determining his fitness for the Premier League visit of Aston Villa, manager Arsene Wenger has confirmed.
The Chile international was left on the bench from the start of the Gunners' FA Cup win over Brighton and Hove Albion but played the last 20 minutes at the Amex Stadium after replacing Theo Walcott.
But Sanchez, Arsenal's top scorer this season with 10 goals in all competitions, picked up a hamstring strain during the week and is now a doubt for the resumption of the club's domestic league campaign.
Wenger has said however that new signing Gabriel Paulista could be available to make his debut against Villa after the club clinched the signing of the Brazil defender from Villarreal.
"The squad will be exactly the same as last Sunday," he said. "The only uncertainty we have is Alexis Sanchez who has a hamstring concern and that will be decided on Saturday."
"He might be out for Sunday. The only [other] difference is that Gabriel is available and we'll check how he is physically but he should be alright to be available."
The news regarding Sanchez comes as a massive blow to Arsenal, who have suffered an injury crisis this season, particularly given it comes less than three weeks before the Champions League last 16 tie against Monaco.
But there is more positive news regarding a series of Arsenal's longer-term absentees, including Danny Welbeck, who after spending a month out with a thigh problem is on the verge of a return for the north London derby against Tottenham Hotspur on 7 February.
"Welbeck is very close," Wenger added. "He is really, really, really nearly there. He will be available for the Tottenham game."
Both Jack Wilshere and Mikel Arteta are on the road to recovery after respective bouts of ankle surgery, while Alex Oxlade-Chamberlain, who missed the cup win over Brighton, is also close to a return.
The manager said: "They are not completely there yet but they are not far. Jack should join in normal training in 10 days. Welbeck on Monday. That's where we are at the moment. Arteta a bit longer."