The two developed and blossomed alongside each other as the Red Devils won the Premier League three times in a row between 2007 and 2009, also claiming a precious Champions League trophy in that time span.
It could be argued, though, that the Portuguese superstar's achievements eventually eclipsed those of his former Old Trafford teammate.
Rooney is certainly a world-class talent, but only Ronaldo's name is mentioned when the debate over the world's greatest footballer rears its familiar head.
Before their meeting on Wednesday in the Champions League Round of 16 clash, here is a comparison of the two, with each ranked out of 10 in six categories.
No matter the final scoreline, both will forever be United legends.
Look forward to see you too tomorrow @waynerooney— Cristiano Ronaldo (@Cristiano) February 12, 2013