Katy Perry Covers Rihanna’s ‘Only Girl In the World’ (VIDEO)

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Katy Perry may have not been able to be with Rihanna for the “Rude Boy” singer’s 23rd birthday but the raven-haired beauty made sure she was with her BFF in spirit by singing her song, “Only Girl (In the World),” during a show in Lisbon, Portugal.

Katy, 26, sang an acoustic version of Rihanna’s hit song on the Barbadian singer’s birthday on Sunday, February 20. At the time, Katy was kicking off her “California Dreams” tour in Portugal but she didn’t let that stop her from celebrating RiRi’s birthday in style.

Katy mixed her best friend’s song with a mash-up of Jay-Z’s “Big Pimpin'” and Willow Smith’s “Whip My Hair.” Watch Katy cover all three songs after the jump.

What do you think of Katy’s version of Rihanna’s song? Share your thoughts in the comments.