Vincent Kompany, the Manchester City captain, is a major doubt for Reading's visit on Saturday and is the latest defensive problem faced by Roberto Mancini as he prepares for the busy festive programme.

Kompany was unavailable for the 3-1 victory at Newcastle last week after limping off in this month's defeat by Manchester United. The 26-year-old saw a specialist after the loss and if his groin injury is more serious than City first thought, the concern for Mancini will be whether he recovers before Kolo Touré departs to play for Ivory Coast at the Africa Cup of Nations finals in South Africa. His last game would be the FA Cup third-round tie against Watford on 5 January.

Mancini is concerned, moreover, as he contemplates an ever-lengthening list of players who will potentially miss matches because of injury and international commitments and just as he attempts to bridge the six-point gap to Manchester United, the leaders.

The availability of Samir Nasri and Mario Balotelli is also in the balance while Micah Richards is a long-term absentee. Abdul Razak, Kolo and Yaya Touré may miss all the club's games when playing at the Africa Cup of Nations, while Aleksandar Kolarov's recovery from a hip injury is unclear after he had to be replaced at Newcastle.

The absence of Kolo Touré, currently the first reserve centre-back, plus Kompany would leave the manager with only two recognised defenders in the position, Matija Nastasic, who is in his debut season at the Etihad, and Joleon Lescott, now the fourth choice.

Jack Rodwell, a versatile if fringe member of the squad, is out until the new year, while James Milner has picked up a hamstring injury and is also an injury concern.

After Reading, City's three other games over the holiday are the trips to Sunderland and Norwich City plus Stoke City's visit on New Year's Day. Nasri could be out for all those fixtures with a groin injury having been forced off in the win at St James' Park.

Balotelli has a virus which means he has missed training this week and Mancini is not confident he will be available to face Reading, with the volatile striker's focus also an issue after he called off taking City to a Premier League tribunal on Wednesday to challenge a £340,000 club fine for ill-discipline.

Rodwell said that he may be out until the new year but on his return he hopes to have more opportunity for regular first-team football when Yaya Touré joins his brother Kolo in South Africa, where Razak may also be a member of the Ivory Coast squad.

Rodwell, a £12m summer signing from Everton who has made only two league starts, has not featured since suffering a hamstring injury in October and suffered a relapse when he first resumed training.

"Yaya would be a big loss for us. He's been amazing so far and has been the engine in midfield, so he would be missed," Rodwell said. "I've just had a little bit of a setback with my hamstring injury. It will probably be another few weeks, so I'm looking into the new year.

"I'm doing quite a lot of training at the minute though, so I'm keeping busy. It's down to strengthening now, so I'm doing a lot of work in the gym and am just getting it right to prevent another injury. It's been a frustrating start to the season and to my City career, bit I'm focused now and I'm ready to get back."

Nasri's potential absence offers an opportunity to Scott Sinclair, another arrival in the summer who has only two league starts. "I've settled in very well at the club," the former Swansea man said.

"Hopefully I'll get a bit more time on the pitch in the new year and get an opportunity to show what I can do. I just want to stay fit, keep working hard and hopefully I will get my chance, and when I do I will grab it with both hands."