This year's surprise South American champions could meet United in the final of the Club World Cup in Japan, which would be another remarkable landmark for the side from Ecuador.
"They're a great side with lots of individual skill," LDU midfielder Patricio Urrutia said ahead of his side's opening match next Wednesday. "They have some real match-winners."
Urrutia has a passion for swapping shirts with opponents after games and admits he will be at the front of the queue for Ronaldo's if they meet in the Yokohama final on Dec. 21.
"I've got more than 100 shirts now," he told FIFA.com. "They're nice souvenirs that my kids can keep always. I collected a lot during this year's Libertadores Cup.
"If we get to the final I would love to swap with Cristiano Ronaldo. I imagine everyone else will also try to!"
The highest salary among LDU's players is around $200,000 -- loose change for Ballon d'Or winner Ronaldo, who earns almost the same amount in one week.
The Quito-based club's ground-breaking Libertadores triumph -- a first for Ecuador -- was all the more astonishing as it was achieved on a modest budget.
LDU WEAKENED
But the sale of key players after their famous victory over Brazil's Fluminense in July, including forward Joffre Guerron and Enrique Vera, has weakened LDU ahead of the Club World Cup.
"I have to run even more now," joked Urrutia, referring to the departure of fellow midfielder Vera. "We're not quite at the level we were but bit by bit we're getting back there."
FIFA's seven-team Club World Cup kicks off on Thursday with Adelaide United playing New Zealand part-timers Waitakere United in Tokyo.
The winners meet Japan's Gamba Osaka with a lucrative semi-final against European champions Manchester United the prize for the victors of that match.
LDU face the winners of Saturday's first quarter-final between Egypt's Al Ahly and Pachuca of Mexico.
Urrutia warned his eagerness to swap shirts with Ronaldo should not be confused for a lack of ambition.
"Sometimes when you lose a game you're so annoyed you either forget or don't feel like swapping shirts," he said. "Hopefully that will happen to our opponents and not us in Japan."
