Sky Sports understands a number of Championship and League One clubs are keeping tabs on Port Vale midfielder Chris Lines.
Lines has impressed at Port Vale since his arrival at Vale Park on a free transfer from Sheffield Wednesday.
The 28-year-old, who is out of contract at the end of the season, has established himself as a key player in Micky Adams' side.
Lines' performances for Vale this season have alerted a number of clubs, with the set-piece specialist regarded as one of the classiest midfielders in the Football League.
Port Vale would be reluctant to lose Lines as they look to maintain their push for the League One play-offs, but could find their resolve tested when the transfer window reopens next month.