The pair had their differences when they were representing their respective countries at Euro 2004, but there's nothing but love and respect between the two Man United legends.
Rooney is United's all-time leading goal-scorer after a glorious spell at Old Trafford. Ronaldo at United for five explosive years and his performances in 2007/08 for the Red Devils skyrocketed him to superstardom and he's never looked back. He's also the record goal-scorer for a European giant; Real Madrid.
Cristiano's game, more and more as the years have passed, became built around power. When he arrived as a teenager from Sporting Lisbon he was slight in appearance and was often bullied off the ball. Now, he's a dominant figure on most football pitches.
Rooney has recently recalled a time when the pair used to train together and Ronaldo wanted to gain weight the night before a game. We certainly can't picture CR7 setting foot in a McDonald's in 2020, considering that the 35-year-old regards his body as a temple. He's more likely to darken the doorstep of his personal gym on leg day.
Rooney has four sons and was in awe as to how his former team-mate—also a father of four— has managed to maintain his incredible physique and training regime: "With four kids I don't know how he fits that in. You've got Ronaldo, who looks a million dollars, whereas I've never had the best body, but I can play 90 minutes, I can train every day. I have no worries physically. When I do, I'll stop."
In an interview with Marca's Pablo Polo and Sergio Fernandez in July last year, Ronaldo hinted that he'd be happy to play until the age of 40 if his body allows for it.
With Cristiano, you just can't rule that out.