Manchester United star Rooney soon became English football's hottest talent, making his England debut a year later before lighting up Euro 2004 at the age of 18.
The pair lined up together for England's World Cup opener against the USA last Saturday and both have important roles to play in South Africa this summer.
While Milner's route to the grandest stage was less direct, he says Rooney's meteoric rise fuelled his own determination.
"I think with Wayne Rooney, there was always going to be comparisons from the time I came through," he said.
"But then he just went to another level and in a way that probably helped me because of the limelight.
"He seemed to take it all off me and that helped me, in that there wasn't that pressure there.
"We see how good he is now but, even then, he went to that other level, pushed into the England squad and, in a way, that helped me."