Ronaldo turned 28 yesterday - 11 years Giggs' junior.
"It's a difficult question to answer, because I do not know where I'll be in ten years, I do not know if I can get to 38," said Ronaldo. "I want to play many more years and I will if I feel good mentally and physically.
"They say that after 32 or 33 years you change your genetics and the way they play, it slows you down, but you gain in experience.
"But I'm enjoying this time, it is very good."