Belgium striker Lukaku has nine goals in 16 Premier League appearances this season and his agent Mino Raiola told talkSPORT that terms for a new deal at Goodison Park were "99.9 per cent" agreed.

Koeman refused to deal in such specifics at his pre-match news conference for the  trip to Premier League champion Leicester City but believes the negotiations are the latest sign of Everton's ambition under majority shareholder Farhad Moshiri.

"I know that [we are] in talks together about a new contract but if it is 90 per cent or 99 per cent… I need to believe his agent," the Dutchman said.

"It's a big deal and the club is showing it wants to keep its best players, doing everything to keep them in the club because that is really the future.

"In football you do not know what can happen in one year but there is understanding. The boy likes to stay and he is a big part of Everton's future."

Raiola stated Lukaku would still assess his options at the end of the current campaign, even if he pens an agreement widely reported to be worth in excess of $171,000 per week, and Koeman accepts this as a reality of modern football.

"They sign new contracts but don't say that they will stay until the end of the contract," he said.

"That's football, that's business – we will see. First of all, I think if the new deal is done that is good news."

A less pleasing piece of news for Koeman is James McCarthy's latest injury absence, with a hamstring strain sustained by the Republic of Ireland international during Tuesday's (AEDT) 1-0 Merseyside derby defeat to Liverpool meaning he will miss the festive period.

"James McCarthy is out, again with a slight hamstring [injury]. It is a shame because the boy was doing well," he said.

"Of course I am slightly worried about [McCarthy suffering] a lot of these type of injuries. He will be out for two to three weeks."

Goalkeeper Maarten Stekelenburg limped off with a dead leg against Liverpool and is a doubt to face Leicester but left-back Leighton Baines will be available despite training away from his team-mates.