However, right-back Luke Young is close to fitness after being out with a knee problem since early December.
Cuellar, who can play at right-back or centre-half, suffered the setback during last weekend's 1-1 draw with Blackpool at Bloomfield Road.
The effect of his absence has been negated to an extent by Villa having a fortnight's break from action. But in any case Young could be back to add competition for back four positions sooner rather than later.
Villa manager Gerard Houllier admitted: "Cuellar is going to be out for four weeks. It is a hamstring tear.
"Luke Young has trained fully for the first time this week and we have a practice game lined up for him.
"The game with Blackburn (on February 26) could be too soon for him but it could be very soon after that."
Young faces a difficult task to oust on-loan Tottenham right-back Kyle Young who was part of the England squad for last week's friendly international in Denmark.
Source: PA
Source: PA