"After they finished rehearsing, I was walking out, and all of a sudden she was walking toward me," Duhamel, 34, says in the July/August issue of Best Life.
"I was like, Oh boy. She stopped. And this is so sad, but I said, in this desperate voice, 'You're hot!'"
"The crush of a lifetime, and that was my line!" he recalls of the September 2004 encounter. "But then an interesting thing happened. She replied, 'Yeah, I read InStyle. So ... how was I in your dream?"
(Fergie, 32, told Playboy earlier this year: "I had read in a magazine that he had a naughty dream about me.")
Now, the 6'3" actor and the 5'4" Black Eyed Peas singer have a new home together. "It's a big house," Duhamel tells Best Life. "A girl like Fergie comes with stuff – a lot of stuff. And there just wasn't enough room for the stuff."