According to the Daily Mirror newspaper, she said: "Harry, yeah. I watch their videos and I remember thinking, 'Wow, he's a star.' He seems very sure. It seems, like, it's so natural to him."
The group are currently staying in the same hotel as the singer in Sydney, Australia , and the boys are trying to find Rihanna - who is Down Under to promote her new movie 'Battleship' - so they can introduce the pair.
A source said: "The boys have been desperately trying to find her. They've been trying to work out what room she's in from her twitter pictures of her view."
However, Rihanna is not the only international superstar who is keen to get to know Harry - who previously dated TV presenter Caroline Flack - better.
Taylor Swift also gushed about his good looks to pal Justin Bieber at the recent Nickelodeon Kid's Choice Awards.
A source claimed: "Taylor is a huge One Direction fan and was excitedly bopping along to the boys when they performed on stage. Then she was chatting to Justin and told him how hot she found Harry.
"Justin was joking about trying to keep his own girlfriend, Selena Gomez, away from the band because she too loves them. Taylor went backstage and was hanging around by the group's dressing room and said a quick 'hello' to the guys.
"She started dramatically fanning herself afterwards making out like she was overwhelmed which got everyone laughing. She really likes Harry but made Justin promise not to go on the record about it."