Manchester: Manchester City manager Manuel Pellegrini admits it`s impossible to know how long knee ligament injury victim Sergio Aguero will be sidelined after the star striker hobbled off in the 1-0 win over Everton.
The Argentina international, the Premier League`s top scorer with 14 goals, limped out in the second minute when he jarred his knee as he stretched for the ball in a challenge with Muhamed Besic.
City`s medical staff will assess Aguero on Sunday to determine the extent of the injury and how long they expect the 26-year-old to be on the sidelines.
Pellegrini has already ruled Aguero out Wednesday`s decisive Champions League game against Roma in which City must better CSKA Moscow`s result against Bayern Munich to progress to the knockout stage.
"It is not good news, I don`t think he will be able to play," Pellegrini said.
"We must wait for the diagnostic, the important thing he will not play against Roma and that is a very important game. It`s impossible to know how long he will be out.
"He has a problem with his ligament in his knee and on Sunday we will know better how serious it is.
"It`s very difficult if you have trouble in your ligament to recover in a few days. Of course it`s a big problem, because Sergio was in a very good moment and is an important player for our team."
Premier League leaders Chelsea slipped to a 2-1 defeat to Newcastle United earlier in the day which meant City`s victory moved to them within three points of the London club.
The victory over Everton came thanks to a Yaya Toure`s 24th-minute penalty and Pellegrini said it proved his side are not just one-man team reliant on Aguero.
"Of course I always say this team is not just Sergio Aguero," Pellegrini added.
"The way we won was important for what we showed in defence. Sometimes it`s important to just win 1-0.
"We had a chance to score another goal and didn`t so I am pleased for the defence because they are criticised a lot, but I thought they did very well.
"It was important for a lot of things. Chelsea lost their game and it was important to recover the points and to be the near the leaders.
"December is a very different month where we have to play a lot of games. It`s a month where maybe you don`t win the title as such, but it is a key month to try to start the next year near the top."
Everton boss Roberto Martinez criticised the decision by referee Andre Marriner to award City the match-winning penalty.
James Milner went down in the area following a slight nudge from Everton captain Phil Jagielka but Martinez felt the decision was a harsh one.
"It was a wrong decision," said the Spaniard. "When you see a ball come into the box, James Milner takes the ball away from the direction of Phil, there was contact but no contact of trying to make a foul.
"Football is a contact sport and for that to be a penalty is a big, big difference."
Everton have now only won once in their last six Premier League games and remain seven points adrift of fourth-placed Manchester United.
But Martinez was satisfied with the response of his players in the second half against City.
"Our confidence left us after the penalty and we couldn`t show what we are as a team. But I thought the performance after the break was good," Martinez added.