Liverpool's Dirk Kuyt and Daniel Agger look set to miss Sunday's Merseyside derby after picking up injuries while on international duty.
Kuyt landed awkwardly during Netherlands' 4-1 victory over Sweden in Amsterdam and appeared to pick up a serious ankle problem.
The forward has only just returned to club action following a shoulder injury.
Meanwhile, defender Agger was substituted in the first half of Denmark's 2-0 victory over Cyprus after suffering a recurrence of a groin injury.
Both will be assessed at Liverpool's Melwood training base before manager Roy Hodgson names his squad for Sunday's derby against Everton at Goodison Park.
Speaking about Kuyt, Netherlands coach Bert van Marwijk explained:"Dirk wanted to play on but our doctor prevented that and told me to substitute him.
"He is now in a hospital but following the doctor's first opinion it could be very serious and keep him sidelined for a long time."