Ronald Koeman and Romelu Lukaku could both leave Everton this summer, warns Ray Wilkins

Everton could lose manager Ronald Koeman if they let Romelu Lukaku leave Goodison Park this summer, according to Ray Wilkins. Talks between Everton and Lukaku regarding a new contract worth £140,000-a-week broke down on Tuesday (14 March), with the Belgian international once again stating his desire to play Champions League football.

Former Chelsea assistant boss Wilkins thinks Lukaku's potential departure could have a snowball effect at Goodison and could cause Koeman, who has been linked with the managerial post at Barcelona, to seek pastures new at the end of the campaign.

"[It was] 99.99% he was going to sign for Everton and all of a sudden there's a spanner in the works," Wilkins told talkSPORT. "They have got to be very careful, because I do believe they have one of the best managers in the Premier League. If the likes of Lukaku do not sign, that will snowball and other people won't sign.

"If you can't bring other [big name] players into the club you might lose a very, very talented manager. I would hate to see that happen because I believe Everton are now improving immensely week after week."

It is believed that negotiations over a new contract for Lukaku, which were '99.999%' complete according to his agent Mino Raiola, stalled over the size of the potential release clause that would be included in the deal.

Everton were looking to insert a clause worth £90m in order to ward off potential interest from other clubs in the summer, but Lukaku and Raiola were looking for a figure around the £70m mark. Talks between both parties are ongoing and the Toffees' majority shareholder Farhad Moshiri issued a statement on Wednesday saying Everton fans needn't worry about the recent news.

Wilkins thinks the reason behind the failure to reach an agreement was not down to an exit clause but due to the length of the proposed terms, and believes Lukaku may well have signed if the deal was a year shorter.

"The only thing I can think of personally is it might be one year too many," added Wilkins. "At 23, five years takes him to 28, [four years until he is] 27 and everybody is happy, he moves on and for a lot of money.

"He has improved immensely as a player because this young man over the next three or four years will become very, very special."