CHRISTINA AGUILERA is providing her with some healthy competition in the bid to out-booty JENNIFER LOPEZ and become the proud owner of the world's most famous backside.

The Dirrty star was pictured arriving at a Christina Dior event in New York looking rather voluptuous.
Since giving birth to baby MAX, Xtina has been working the curvy look by wearing tight-fitting outfits that have given her famous pregnancy boobs maximum exposure.
But, now her boobs appear to be shrinking, it seems her rear has become the main attraction.
May the bum battle commence...

From : http://www.thesun.co.uk