"Rafael left early because his calf tensed up which could mean that he pulled it slightly," coach Bert van Marwijk told a news conference.
"He was bothered after Thursday's match (against Cameroon) but yesterday he completed the whole training session, so I can't estimate at this stage if he can play tomorrow."
The Dutch team's most potent attacking weapon, Robben made an immediate impact as a late substitute in their final Group E match against Cameroon when his shot hit the post and striker Klaas-Jan Huntelaar netted the rebound to secure a 2-1 win.
"Arjen felt no reaction to his hamstring after the Cameroon match and I speak every day with him but in the end it will be my decision (whether he starts)," Van Marwijk added.
"You see many teams having a poor spell after they have taken the lead, but we suffer from that more than most," Van Marwijk said.
"We seem to believe that we can sit on the lead, but we cannot afford to do that, especially not in this phase of the competition.
"We did it the first two matches and stayed in control but against Cameroon for the first time I had the feeling we could have lost," he added referring to their 2-0 opening win over Denmark and 1-0 victory against Japan.
