On-loan Fulham striker Aleskandar Mitrovic could reportedly cost up to £20m, should the Cottagers be interested in tying the Serbian down to a permanent deal.
The Newcastle forward, who joined Fulham on loan in January, scored 12 goals for the West London club to help push them to promotion back to the Premier League.
Mitrovic is heading to the World Cup with Serbia and could cost the Cottagers £20m if the 23-year-old impresses in Russia.
Fulham midfielder Tom Cairney has urged the club to sign the striker on a permanent deal.
"We have got to try and sign him," the midfielder told reporters. "He is a Premier League centre-forward. He is going to play for Serbia in the World Cup and if he scores goals there then more people are going to be in for him. I think he loves it here and he loves the manager.
"We are an attractive club to come to. "We have been in the Premier League for a long time apart from the last few years, we are in London and the style of play is attractive. We look to play football and score goals."
Fulham join Wolverhampton Wanderers and Cardiff City in ascending to the top flight next season.
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