Cristiano Ronaldo is dealing with patellar tendinosis in his left leg.

The Portuguese FA (FPF) announced on its official website that Ronaldo is suffering with a "muscle injury on the back of his left thigh as well as left-leg patellar tendinosis" as he works to be available for the Group G opener on June 16.

Portugal winger Nani was quoted on FIFA.com as saying Ronaldo was "going well" and is "relaxed" about his fitness troubles.

"We hope that Cristiano is in good enough shape to play -- and to help the team," Nani, who played alongside Ronaldo at Manchester United, said. "If for some reason he is not there, whoever is there playing has to be confident in their ability to get the job done."