The singers join forces for a weekend concert in Sin City. Plus: Natalie Portman, Gavin Rossdale, Jason Derulo & more!

POWERFUL PAIR

Reese Witherspoon and Jennifer Lopez make a stunning sight in matching red and black dresses at Variety's Power of Women event (sponsored by Audi, Moroccanoil and Saint Vintage) at the Beverly Wilshire Four Seasons in Los Angeles on Friday.