Fulham are chasing Celtic defender Dedryck Boyata.
The Daily Mail says the Parkhead club are highly reluctant to sell the 27-year-old as they prepare for a Champions League third round qualifier with AEK Athens.
Fulham boss Slavisa Jokanovic is expected to step up efforts to land Boyata before the English transfer window closes on Thursday.
The club have spent £15m on Swansea defender Alfie Mawson, but he is not likely to be ft until September.
Forced to go with the inexperienced pairing of Jack Hendry and Kristoffer Ajer against Rosenborg, however, the Premiership champions have not yet given up hope of persuading the former Manchester City defender to sign a new deal.