Despite suffering an injury at the weekend, the Manchester United player should be ready to feature against Joachim Low's side on June 9.
"Yes, it was a scare. It was a very dangerous challenge, I was in a lot of pain, I still am a bit, but I think I will recover well in the next few days," he told reporters.
A fitness test conducted by the team doctor revealed that the 25-year-old suffered an injury to his right foot, a problem that surfaced during the season.
However, it was described as not being very severe, and Nani, who scored during Portugal's 3-1 home defeat to Turkey, is confident of being ready for the opening clash.
"We will see when I return to Portugal's camp. It may have caused a small strain. I believe I can play against Germany," Nani said.
The winger has five days in which to continue his recovery before facing the Germans. Group B also includes Denmark and Netherlands.
Nani has netted 13 times in 54 games for Portugal since making his debut six years ago as a teenager.