One Love: U.S. Open Couples!

From Chelsea Clinton & Mark Mezvinsky's PDA to Gwen Stefani & Gavin Rossdale's cheer section, see which star pairs are Grand Slam fans!

ASHLEE & PETE

Looks like Ashlee Simpson-Wentz is more of a tennis fan than hubby Pete! The singer took a stand to cheer on Federer at his Sept. 6 match against Austria's Jürgen Melzer. Also in the couple's box: pal Cameron Diaz, whose rumored beau Alex Rodriguez was watching the match courtside.