Manchester City's recent loan signing Nery Castillo faces around six weeks out of action due to a shoulder injury.
The 23-year-old Mexico international only joined the Citizens recently on a year-long loan from Shakhtar Donetsk, but faces time on the sidelines after sustaining a broken bone in his left shoulder in the FA Cup win over West Ham.
City boss Sven-Goran Eriksson said: "He does not need surgery on the injury, but he will be away for between five and six weeks.
"He is very unlucky and he's the player we need as well."
Meanwhile, Eriksson has backed Castillo to prove his worth on his comeback, telling the Manchester Evening News: "Nery is settling in well. He is a good young footballer, there are no doubts about that.
"People have to remember that he has come in halfway through a season having not played much at all for Shakhtar.
"It is not easy for him because English Premier League football is so different. He has less time on the ball than he is used to and you can see that sometimes.
"That is where he loses out, but he has to taste the competition to get better and he will do, I am sure.
"He is still young and we have him on loan until halfway through next season and we will see him improve."