You never know when or where celebrities are going to pop up these days and you can only imagine how surprised a crowd in Moscow must have been when Steven Tyler showed up for an impromptu duet with a street musician.

Tyler and his entourage were strolling the streets of Moscow when they encountered a young street player and he just happened to be playing "I Don't Want to Miss a Thing." Tyler listened for a bit then strolled up and launched into the song. The crowds reaction was pretty amazing, but in watching the video, one get the idea that the young minstrel either didn't recognize Tyler (not likely) or he was just too stunned to really react.

Let's hope that the duet made plenty of money for the street singer.By the way, you gotta love Tyler's coat!