Aston Villa could be without Spanish defender Carlos Cuellar for up to a month after he tore a hamstring.The news will come as a blow to Gerard Houllier, whose team have been in good form of late.Villa slipped into the relegation zone in early January, but nine points from their last six games has taken them to 15th in the English Premier League.They also have a fifth-round FA Cup tie to look forward to, against either Manchester City or Notts County.Of Cuellar's injury, Houllier said: "He is going to be out for four weeks. It is a hamstring tear."Meanwhile Villa - who have a two-week break between games - could see full-back Luke Young return to action for their next Premier League game, against Blackburn Rovers on February 26."Luke Young has trained fully for the first time this week and we have a practice game lined up for him," said Houllier."The game with Blackburn could be too soon for him but it could be very soon after that."