Cape Town - Manchester City will be without captain Vincent Kompany for the derby against Manchester United this weekend after the defender suffered a recurrence of a calf injury.
The Belgian has started just 13 Premier League games for City this season, but he was back in the starting line-up for the Champions League last-16 return leg against Dynamo Kiev on Tuesday evening.
However, he lasted only seven minutes before he had to be substituted with yet another calf injury and manager Manuel Pellegrini confirmed he will be out of action for at least a month.
"Vincent, unfortunately, has a muscle injury in his calf like he had before," he said.
"We'll know more tomorrow or maybe the day after tomorrow how important it is, but always a muscle injury is minimum of one month."
Kompany has now had 14 calf injuries since joining the English Premier League club in 2008.
"I think Vincent must be very strong mentally," Pellegrini said.
"It's very difficult to accept but he has nothing else to do," his manager said.
City lost both their centre-backs in the first half as Nicholas Otamendi went off after a collision with another player, but it doesn't appear to be too serious.
Pellegrini added: "Otamendi has an important kick but we think just a couple of days for him to recover. We will see the way he develops."