Roberto Mancini's relief at Manchester City keeping their slim hopes alive of retaining their Barclays Premier League title was tempered by another injury setback to Jack Rodwell.
A first half goal from Carlos Tevez was sufficient to earn City a 1-0 win at Aston Villa and cut the gap on leaders Manchester United to 12 points.
But midfielder Rodwell suffered a recurrence of his hamstring injury midway through the opening period and will be sidelined for "three to four weeks".
Mancini said: "We are very sorry for Jack, because he is a good guy, a good player, but he is unlucky. It is his hamstring.
"I think it is impossible to resolve his problem after six or seven months because he's had this problem for five or six years and we need maybe more time.
"How long will he be out? Maybe he will be back after the international break, three or four weeks. It is the same injury.
"I am very sorry because he is a young player. He needs to improve but he has played very well against Chelsea and was playing very well tonight."