Tom Cruise's character, Stacee Jaxx, sings the 80s group's Pour Some Sugar on Me in the musical film, and they were surprised at exactly how quickly he had got good at singing when they turned up to filming in Florida.
Singer Joe Elliott said, "It was pretty surreal, actually. We just walked into this little seedy club in Ft. Lauderdale, and there up on stage is Stacee Jaxx doing Sugar. It's like, 'What is this?' It's nuts."
When asked what they thought of the song, bass player Rick Savage said, "His voice was good."
Joe added, "We were talking to him between takes, he said, 'What do you think?' I said, 'Can you sing?'
"He said, 'No, I started like four or five months ago, just a couple of hours a day.'
"He had other movies he was shooting, so it was like a part-time thing. I'm thinking, 'Wow. If he's got that good in four or five months, that's much better than half the people on some of these talent shows.'"
Earlier this week, Tom revealed that he took home a memento from his time playing the rock star for the film - a bejewelled, dragon-shaped codpiece, used in a scene where he beds two women, for his wife Katie Holmes.
When asked how she reacted to being presented with such an interesting souvenir, he said, "She laughed. It's hilarious."
