Battle of the amazing booties!
Beyonce showed off her most famous body part at Sunday night's Glastonbury Music Festival in England, where the 29-year-old donned a sequined gold jacket and skimpy black leotard.
PHOTOS: Beyonce's amazing bikini body
Days later, Rihanna, 22, challenged the stunning wife of Jay Z's "bootylicious" status when she stepped on stage in her own colorful and rear-revealing ensemble during her Loud Tour at the Staples Center in Los Angeles.
Both pop princesses looked absolutely amazing in their risque costumes, but who flashed their bum better? Vote now!