كتب : Hatem Maher
The 25-year-old was stretchered off the pitch with 12 minutes remaining before being taken to hospital on crutches.
"Wesley told me he heard something crack so it looks serious but we have to await the outcome of the investigation in the hospital," Holland coach Bert van Marwijk told reporters.
Sneijder, who joined Italian champions Inter from Spain's Real Madrid last week, scored Holland's second goal against Japan.
He excelled in his debut with Inter when the Nerazzurri crushed arch-rivals AC Milan 4-0 in the Serie A.