Southampton boss Ralph Hasenhuttl admits they risk losing Jannick Vestergaard this summer.
Danny Ings is also now inside the final year of his contract at Saints.
Hasenhuttl said: "It's getting harder and harder to extend with players these days. It can be seen. The whole system does not work as it should in my optics.
"Players can speculate about leaving clubs on a free transfer, and thus switch wherever they want.
"It is a problem for the smaller clubs, because we have paid a lot in transfer fees. For Danny Ings we paid a lot of money, and we did the same for Jannik Vestergaard.
"So it is quite difficult to extend with players. Times have changed and it is no longer so interesting for players to become legends in clubs.
"It's not good for football, but that's the market, and we have to play the game like other clubs."
