Roberto Mancini says he is hopeful skipper Vincent Kompany will be fit within the next two weeks after the Belgian limped out of City's 1-0 defeat to Sporting Lisbon.
Kompany will now miss the trip to Swansea, the second leg against Sporting and possibly the home game with Chelsea unless he recovers quicker than anticipated.
"We have to wait one or two days to know the exact extent of his injury, but it is a problem with his calf," said Mancini.
"I hope to have Kompany back in 10 days or two weeks, but we have other solutions. This result was not a surprise, anything can happen in football. I don't think we deserved to lose.
"We did not play well, we had chances to score, but we didn’t take them. It will be a different game in Manchester. When we have chances to score, we will score."
Mancini admitted he was surprised Sporting played for long periods as though they were the away side, defending very deep and trying to hit the Blues on the break.
"I don’t think Sporting had a lot chances to score," he said.
We played like we did because Sporting played with all their men behind the ball for 90 minutes - they wanted to hit us on the counter-attack
"We played slow sometimes because we found ten players behind the ball. We had more chances to score than Sporting, though we did not underestimate them.
"Every game is difficult and different, we tried to play good football, sometimes we can, sometimes we can’t. Football is strange. We have another game and we have more chances to win the next game and I think we will progress in this competition."