Minutes from the end of the 3-1 win over Slovenia on Sunday, the defender left the field on a stretcher and in obvious pain after his leg buckled under him.
The Celta Vigo man has issued an upbeat bulletin, contradicting early fears that he may miss the remainder of the tournament.
He said: "I went over on my left ankle but I've got flexible ligaments.
"I left the field because I was in a lot of pain but the ligaments snapped back into place and, despite the fact that there is a bit of swelling, I'm sure I'll be ready to play against Paraguay, if I am needed by the coach."
Deportivo La Coruna`s Enrique Romero is the obvious replacement, should Juanfran fail to make a complete recovery before Friday.
