Kate Walsh attended the men's singles semifinal match between Rafael Nadal of Spain and Mikhail Youzhny of Russia at the 2010 U.S. Open in New York, and all we have to say is, who knew the Private Practice starlet got so pumped about tennis?

Then again, Charlize Theron got pretty into it as well:

Charlize Theron US open sunglasses tennis

Wonder which one they were cheering for?