Fulham boss Slavisa Jokanovic is chasing Young Boys defender Kevin Mbabu.
Sky Sports says Fulham are keen on signing Mbabu but face competition from Swiss side FC Basel.
Basel are understood to have had an offer of £7m rejected by their Swiss counterparts, who are believed to value Mbabu at £10m.
Fulham are yet to bid for the 23-year-old, who joined Young Boys from Newcastle United - initially on loan - two years ago.
Mbabu, who is primarily a right-back, could replace Ryan Fredericks, who left Fulham to join West Ham after his contract at Craven Cottage expired this summer.