Holland could be without Maarten Stekelenburg when they face Moldova and Sweden, as the goalkeeper undergoes further assessment on his head injury.
Stekelenburg has missed the last three fixtures for his club side, Roma, because of a head injury suffered in a clash with Lucio early on in his side's goalless draw with Inter Milan last month.
And he is now a doubt for the Euro 2012 qualifiers with Moldova and Sweden over the next week.
A statement on www.onsoranje.nl read: "Maarten Stekelenburg headed on Monday for the training camp in Noordwijk, not with the Dutch team.
"The goalkeeper is undergoing further investigation following the head injury he suffered two weeks ago in the league game for his club Roma against Inter. This will show whether the goalkeeper can be part of the squad."
Holland, who have already qualified for Euro 2012, host Moldova on Friday before heading to Sweden four days later.