Pippa Middleton: Roger Federer Quarterfinal Match Spectator!

Pippa Middleton socializes with Roger Federer‘s wife Miroslava Vavrinec at the U.S. Open Tennis Center on Wednesday (September 5) in New York City.

Earlier that night, the 28-year-old younger sister of Catherine, Duchess of Cambridge watched her friend Roger Federer lose his quarterfinal match against Tomas Berdych at the 2012 U.S. Open.

PHOTOS: Check out the latest pics of Pippa Middleton

During the day, Pippa donned bright red pants while visiting some friends in New York City.

The day before, Pippa was spotted enjoying some tennis.

FYI: Miroslava is carrying a Valentino bag.

20+ pictures inside of Pippa Middleton visiting friends in New York City…