Speculation has been rife that there is an underlying issue as Nani travelled with the rest of the squad to South Africa and trained with them for two days after suffering the injury before being ruled out.
And the Manchester United winger has now added fuel to the fire by telling awaiting reporters at Lisbon airport: "I'll be fine in a week."
If Nani's claims are true, the 23-year-old would have only missed Portugal's opener against the Ivory Coast and would have recovered in time to face Brazil and North Korea.
The vice-president of the Portuguese federation insists there are no problems between Nani and the coaching staff.
Amandio de Carvalho said: "There is no attempting to hide anything, there was only the hope that he could have recovered."
Nani was looking to shine in the showpiece event after an impressive season for United.
He said: "I thought this was going to be my World Cup, I was training and playing well, but that's life.
"I worked a lot for this World Cup but I had the misfortune to injure myself before the start."
Nani had struggled to hold down a regular first-team place at United following his switch to the Premier League from Sporting Lisbon in 2007.
But he emerged from the shadow of Cristiano Ronaldo following his compatriot's move to Real Madrid last summer and became an integral part of Sir Alex Ferguson's side as they narrowly lost out in the title race to Chelsea last term.