The pair are former Manchester United teammates.
"As soon as I arrived, the first person I met was Ryan Giggs," he said.
"We're talking about a player who could've also been my father! It was a shock to see him.
"Cristiano, on his part, always wanted to improve.
"He was constantly wanting to be the best: he behaved like it on and off the pitch.
"In the gym, it was another challenge. He always wanted to be number one."