The goalkeeper suffered a calf injury during Spain's 1-0 defeat to South Africa and could now miss key games for his club.
The 31-year-old replaced Iker Casillas at halftime during Spain's 1-0 defeat to South Africa on Tuesday but was then carried from the field in the 75th minute after suffering what appeared to be a torn calf muscle.
Valdes - who is set to leave Camp Nou on a free transfer at the end of the season after opting not to extend his current deal - will undergo a scan in Barcelona on Wednesday.
After the game, the Spanish Football Federation confirmed news of the keepers' impending absence, with doctor Oscar Celada stating: "If the injury is confirmed, he will have to be out for several weeks."
Vicente del Bosque hit out at his Spain side on the back of the defeat in Johannesburg - which came in same city where they lifted the World Cup back in 2010.
The loss comes after la Roja scraped past Equatorial Guinea with a 2-1 win last week.