Sunderland fullback Phil Bardsley admits they're worried about losing Simon Mignolet in the summer.
The Belgian goalkeeper has been linked with Arsenal in recent days.
Bardsley said: "He is unbelievable, but we don't want to pump him up too much in case someone comes in and tries to buy him! But he is a talent.
"When you think of the broken nose and cheekbone he sustained last year against Aston Villa, for him to still come flying out at people - he is exceptional. He's a beast."