Manchester City boss Roberto Mancini regrets not signing an extra defender during the January transfer window.
Mancini wishes he had moved to bolster his rearguard after captain Vincent Kompany was injured in the FA Cup fourth-round win at Stoke on January 26. At the time City did not expect the 26-year-old's calf problem to require a lengthy lay-off but he has not played since and Mancini feels his absence has been a "big problem".
Mancini said: "Probably we made a mistake because when we knew (of) this problem we were four days to (the) close (of) the market. Probably then we should maybe have bought another defender."
He added: "Also, last year he had this problem, for one month he didn't play. This is a big problem. For me we did a mistake in this case.
"We had a chance because we had one good defender but we didn't think that Vinny would stay out for 40-45 days."
City have also been without two other defenders in Micah Richards and Maicon through injury but their only major transfer activity in January saw striker Mario Balotelli leave the club.
Kompany's prolonged absence has raised fears he may require surgery or miss the rest of the season but Mancini continues to play down the seriousness.
He said: "He starts to run and we hope that he will be ready for Newcastle.
"He started with us three or four days ago but he was tired because he worked a lot. His calf was tired but he didn't have any problems.
"But we don't want to take a risk at this moment because we have one game and after it is the international break. It is better we wait."