Former Portugal coach Carlos Queiroz has warned the country could struggle at the FIFA World Cup if Cristiano Ronaldo is not on top form.
Ronaldo featured in Portugal's opener as they were comfortably dispatched 4-0 by Germany - with the Real Madrid star having struggled with injuries in recent months.
Reports suggest Ronaldo is still suffering with a knee problem, casting doubt over his future participation, and Queiroz feels Portugal will suffer without him at his best.
The pair exchanged frank views about Portugal's exit in 2010 when Queiroz was in charge and the current Iran boss says Ronaldo needs to perform in Brazil.
"The story of the world's great teams is always made by great players and stars. By this I mean that Portugal cannot think of having success with the Cristiano Ronaldo of the 2010 World Cup," he told Publico.
"For Portugal to get far in Brazil, we need the best version of Ronaldo. Only he can make the difference but if he plays like in South Africa we will have less chance.
"I hope this injury does not affect his performance."
After Portugal were beaten in the last 16 by Spain four years ago, Ronaldo reportedly said people should "ask Quieroz" why the loss occurred.
Despite their disagreements, Queiroz insists he holds no grudges against his compatriot.
"I am not distant from him or indifferent. We don't owe things to each other. I was his coach and friend, inside and outside the pitch," he added.
"Now, if Cristiano, one day, understood that he should treat me in that way, although I was not expecting it, I have to respect.
"I don't have anything against him, but I still think that this behavior was not opportune, considering his role as captain of the national squad. Honestly, I didn't like it and I would be an hypocrite if I denied it."