"If Romelu was to play at Everton until the end of his career I know he has left something behind"
Everton manager Ronald Koeman has acknowledged that Romelu Lukaku's long-term future will naturally see him move away from Goodison Park.
The Belgian forward has often been linked with transfers to some of Europe's biggest clubs since he moved to the Toffees permanently from Chelsea in 2014.
The Anderlecht youth academy product's current contract runs out in 2019.
The 23-year-old recently scored his 50th Premier League goal since joining Everton, with 68 goals in total in all competitions.
Speaking to Belgian newspaper HLN, Koeman admits that his vast potential means Lukaku will one day depart the club.
"His potential is greater and higher than Everton as a final destination. If Romelu was to play at Everton until the end of his career I know he has left something behind," he said, also drawing comparisons with former Netherlands striker Patrick Kluivert who eventually left for AC Milan and then Barcelona after emerging from the Ajax youth ranks in the 1990s and scoring the winner in the 1995 Champions League final against Juventus.
The former Southampton boss said he had convinced Lukaku to remain ahead of this season but is unsure about what will come beyond this campaign.
"I gave him confidence and he has himself recognised that it was good for his development to play another year at Everton. There is a very good contact and appreciation between us. What after this season comes, no-one knows," he said.