Manchester City striker Sergio Aguero has been ruled out of his side's FA Cup third-round clash against Watford on Saturday.
The Argentine suffered a hamstring injury during City's 3-0 home win against Stoke City in the Premier League on Tuesday and had to be substituted in the 77th minute.
"It's difficult to assess an injury like that and how long it is going to be," BBC Sport quotes City's assistant manager David Platt as saying.
"Certainly on Saturday he will be out and my experience would say he will be doubtful for Arsenal [on January 13]. But it is far too early to tell.
"There will be a lot of swelling in there and a bit of bleeding and, to be honest, we won't know for 48 hours how quickly it is going to settle down."
City are currently seven points behind leaders Manchester United in second place in the league.
