Manchester City striker Sergio Aguero is out of Saturday's FA Cup third-round tie against Watford after picking up a hamstring injury against Stoke.
The injury means that the Argentina forward is also a major doubt for their Premier League trip to Arsenal on January 13.
Aguero suffered the injury moments after scoring a penalty that rounded off a 3-0 victory over Tony Pulis's side.
City assistant manager David Platt confirmed that the striker faced a spell on the sidelines, although added that it was too early to tell how long he would be out for.
Platt said: "It's bad enough that he won't play on Saturday. It's difficult to assess, with an injury like that, how long it's going to be. Saturday, he'll be out. My experience would be that he'll be doubtful for Arsenal.
"There are different degrees of hamstring injury. That's why you need the 48 hours to assess it. It's not just cut-and-dried that, because it's a hamstring injury, that's how long it's going to be. We don't know yet.
"It's far too early to tell. There'll be a lot of swelling in there, a bit of bleeding and we won't know for 48 hours how long it's going to be. It's a blow but unfortunately, when you have got so many games in a short space of time, you are running the risk with everybody.''
Aguero had previously missed a month of action earlier in the season with a knee injury sustained in the 3-2 home win over Southampton on the opening weekend of the season.
On a more positive note, fellow forward Mario Balotelli appears to be recovering after a virus. The Italian has missed the last four games with the condition but is now back in training.
Platt said: "The problem was he was ill, came back and trained and had a relapse with the illness so went back down again.
"It looks as though he has got past that now. He has had two or three days' training and will have another few days before the game at the weekend. There is every chance he will be available for selection.''