Everton midfielder Idrissa Gueye is in talks over a new deal, sources close to the player have told ESPN FC.
Gueye has impressed at Everton since arriving from Aston Villa last summer, establishing himself as a key part of manager Koeman's plans.
He made 35 appearances in all competitions in his debut season, with his displays alerting a number of Premier League rivals as well as clubs from overseas.
But Everton are keen to fend off any interest in the player by tying him down to a new long-term deal, with improved terms to bring him in line with other top earners.
Everton are determined to keep hold of their best players as they look to make a sustained bid to break into the Premier League's top four and qualify for the Champions League over the next few seasons.
Securing Senegal star Gueye on a new deal will come as a welcome boost to Koeman after a difficult run of form in recent weeks.