Aston Villa will reportedly release Carlos Cuellar to Rangers if his old club improve their bid.
Rangers owner Craig Whyte confirmed this week that the Ibrox club had made an offer for the central defender, thought to be in the region of £1.5m.
While new Villa boss Alex McLeish is wary of losing too many players, it is understood that the club may be persuaded to let him go if the bid were improved to £3m.
The 29-year-old, who joined Villa from Rangers for £8m three years ago, made 16 appearances last season before undergoing knee surgery.