The 25-year-old is currently with the Netherlands squad at the World Cup and was speaking at a press-conference ahead of Tuesday's clash with hosts Qatar alongside his coach Louis van Gaal.
De Jong looked a bit pale at the media session and when asked about his health, the playmaker allayed fears that he would miss the clash.
"I'm fit - I just have a sore throat and didn't sleep that well last night. But I feel great," said De Jong.
A win over Qatar would secure the Oranje's place in the knockout stages after a 2-0 win over Senegal and a 1-1 draw with Ecuador sees them top of the group with four points. Ecuador also have four points, while Senegal have three, meaning it will go down to the final round of the group stage.