Both defenders are believed to be nursing injuries, and will sit out the first friendly match of Everton’s 2016/17 pre-season schedule.
The Dutchman will, however, be able to hand 45 minutes to action to his returning international stars.
Of the seven returnees, Koeman said: “We have the players back from the Euros and they will play 45 minutes and that is good because they need to work.
“It is always tough against English teams, we need those kind of friendlies to prepare for the Premier League season.
“For them to play a Premier League team is a nice challenge for them to look forward to. It’s not always the result that is the most important thing – what you like to see is the team improving technically and physically.”