We can all agree that when it comes to sex appeal, Shakira's got it in spades.  But Shakira herself says that when it comes to oozing sex, there's one woman who trumps her: her new duet partner, Rihanna.

"Working with her was utopia. She’s the sexiest woman on the planet," Shakira tells Glamour for the cover story of the magazine's February issue. "A the end of the day, we’re both just basically Caribbean girls. The chemistry was so good and so real. She taught me dance moves. She was a sweet teacher.”   Shakira and Rihanna's new collaboration, "Can't Remember to Forget," debuts January 13.

Elsewhere, Shakira discusses returning to NBC's The Voice as a coach, which she will do next month, along with Usher.  "Dealing with boys at work and being the only girl can be challenging. I have my insecurities, but I’ve learned I have to be a good sport," she tells Glamour. "I have to be able to take certain jokes and not take them personally...I had to develop a tough hide."

Shakira, whose son Milan will turn one on January 22, also talks about her appearance, specifically about whether her Latin fans have criticized her for dying her hair blonde, or not being curvy enough.  "At the beginning," she reveals. "But my man Gerard [Piqué, Milan's father] prefers meat over bone.  He doesn't like too skinny.  That takes pressure off."

"I already have a lot to worry about," she continues, regarding her body. "This month I’m not exercising because I have an album to finish and I have a baby. And I like these pastries in front of me.”