Manchester City captain Vincent Kompany will miss the Premier League champions' trip to struggling QPR on Tuesday with a calf injury.
The Belgium defender limped off after 33 minutes of City's FA Cup fourth-round win over Stoke at the Britannia Stadium and first-team coach David Platt confirmed he faced a spell out.
The news limits manager Roberto Mancini's defensive options at a time when Kolo Toure is on international duty at the African Nations Cup.
Platt said: "He has pulled his calf. We won't know how bad it is until the morning but there won't be any chance of Tuesday."
Remarkably it took City seven minutes to replace Kompany, who pulled up and headed straight down the tunnel, but City battled through to win 1-0 with a late Pablo Zabaleta goal.
Zabaleta struck from close range after 85 minutes as City, who had been dominant in the early stages, finally wore their resilient hosts down.
Platt said: "The pleasing thing is we battled hard, defended well and kept another clean sheet.
"It is pleasing from that perspective and it is also pleasing to go through.
"We knew it was going to be difficult here. You know the ball is going to come in the box and you're going to have to compete for first balls, second balls all day.
"It is the way it is going to be and I thought we did it well."
The goal was Zabaleta's third of what has been an outstanding season for the right-back.
The 28-year-old Argentinian has been one of City's most consistent performers throughout the campaign and Platt hailed his down-to-earth attitude.
He said: "When you have got players of the ilk we have got - the Yayas, Silvas, Agueros, Tevezes - they all work hard and do what they have to do, but you need to sprinkle into that mix those players that often go under the radar.
"What is pleasing is that he scores a goal in a cup match and he can get some headlines, but he won't be bothered about that.
"He isn't bothered about headlines. Those kind of players aren't.
"It's not what they play for. He is an eight out of 10 man every week. For professionals he is just a top man really."
Platt added that Zabaleta's latest strike was no fluke.
He said: "We get players into advanced areas. It is not by luck Zaba gets into those positions.
"The way we play we get a lot of players forward. Zaba has been in those positions many times and he tucked it away nicely."
Platt could not comment on the one moment of controversy in the game when Stoke's Glenn Whelan escaped punishment for a two-footed tackle on City midfielder Javi Garcia early in the second half.
Garcia required treatment and later had words with referee Howard Webb.
Platt said: "I haven't seen it so I can't comment on it. Somebody said it wasn't good. But the referee was right there and had a good view of it."
Stoke manager Tony Pulis also said he did not have a clear view of the incident.
Pulis said: "I haven't seen the challenge, I will have a look at it."
Pulis had no complaints about the result and felt his team had paid for trying to take the champions on.
He said: "We played more open than we normally do at home.
"In a cup tie you want to catch them and have a go at them.
"You have got to give City a lot of credit. Their attitude and approach was first class.
"By playing as open as we did, against the best teams, it always gives them a chance to attack and create chances. I thought they did that well.
"Although we are disappointed to have lost the game, and lost it in the last few minutes, you have got to give City a lot of credit.
"Unfortunately when you come up against the best teams, they need to be a little below par, you need to be right on top of your game and we weren't right on top of our game today."