Fulham and Newcastle United are among clubs ready to pounce for Hearts captain Christophe Berra.
Hearts boss Csaba Lazslo has confirmed the interest of Chelsea and Manchester United in the Scotland defender, though a move to either Premiership giant is unlikely in January.
Former Jambos coach Steven Frail conceded: "It's no surprise to me that a club like Hearts may have to sell players to balance the books in January. In the current financial climate, all clubs have to look at it.
"But, if at all possible, the one player I think they should try to hang on to is Christophe. If I was still working at Hearts, he would be the player I'd try to sell last.
"If they lose Bruno Aguiar, they will lose an inventive midfielder, but there are others waiting in the wings to slot in. The same goes for Kingston, but Berra's situation is different. There isn't the same replacement for Christophe, so selling him could be a bigger loss than Craig Gordon was."