It has been suggested that Pienaar exaggerated the injury following his country's poor showing but the Borussia Dortmund midfielder has reacted angrily to such claims.
"This is just nonsense. I am injured and will be out for three weeks," Pienaar is quoted in the Liverpool Daily Post.
"I am not that stupid and I don't care what anybody says. I was having a good tournament and would have loved to play."