Manchester City boss Manuel Pellegrini is concerned about the amount of action captain Vincent Kompany is missing.
The influential defender is currently sidelined with the thigh injury suffered in City's victory over Everton five weeks ago.
It is the 27-year-old's second lay-off of the season after he missed three matches with a groin problem incurred in the opening game.
The Belgian was also sorely missed as he spent two months out with a calf injury at a critical stage of last season and he had a similar problem during the 2011/12 title-winning campaign.
Pellegrini said: "Of course we are concerned about that and we are trying to do all the best to see how we can improve in that sense."
Kompany will miss Sunday's English Premier League trip to Sunderland but Pellegrini is hopeful he will return after the upcoming international break to face Tottenham on 24 November.
Pellegrini said: "He has two weeks more. We hope if he continues the same way he will not have any problems."
There have also been reports that Belgium are concerned enough about the time their national skipper is spending out to have sent their own physiotherapist to Manchester to assess him.
"I don't know about that," Pellegrini said.
Kompany was this week joined on the sidelines by playmaker David Silva, who was withdrawn after 66 minutes of the UEFA Champions League win over CSKA Moscow on Tuesday with a calf injury.
The Spain international could now be out of action for a month.
Pellegrini said: "He has a problem with his calf.
"I don't exactly know how many weeks it will be but maybe three or four."
As a key player for Spain, for whom he played in the FIFA Confederations Cup in the summer, Silva has had a particularly heavy workload.
Pellegrini accepts that is something he must deal with in the modern game.
The Chilean said: "I don't think it is only Silva.
"We have an important squad here, and now in the international break next week we will have just four players.
"All the other players play exactly the same, not only David Silva."
Despite the continued absence of Kompany and the injury to Silva, it has been a good week for City.
It began with a 7-0 thrashing of Norwich and the 5-2 defeat of CSKA that followed ensured qualification for the Champions League last 16 for the first time.
City exited at the group stage under former boss Roberto Mancini in each of the past two seasons but Pellegrini, appointed in the summer, refuses to take much credit for the change in fortune.
The 60-year-old said: "I don't think the major important (factor) was me.
"The club decided to make the change, I was (made) the manager for the whole year.
"The Champions League is just one competition we are involved in this year.
"It was an important achievement but the first one.
"I think I can do better things with the team this year. We will see what happens at the end of the season."