The Irishman's life has changed dramatically since the 2004 FA Cup final.
Speaking to the Independent, the Irishman said: "Ronaldo was thin but tall, more than I thought. Then of course, cool: you saw that he would become an incredible player. Maradona was great, but he and Lionel Messi are perhaps the strongest ever.
"Now I can tell it, 'I tried to mark CR7'. I never talk about games but I remember that after 3-4 minutes a ball bounced in my area, I could have spread it out but I didn't want to play the whole game with a yellow. Let's say that from then on it was tough: unfortunately he played on my side..."
Following the 2004 FA Cup final, which Manchester United won 3-0 with Ronaldo scoring the winner, Ryan played for the likes of Bristol Rovers and Welling United before retiring for good and changing careers.
The 43-year-old former full-back added: "Now I work for the London Underground: I work as a metro worker, I repair the lines when the trains are stopped. I didn't get rich with football, but I like the job, I have a nice family and I don't miss the ball."
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