Mostly evryone has given thoughful answers to this. For me, and the people that I've associated with who are Tennis Fans and happen to be Americans just simply appreciate Talent regardless of where that Player bornes from.
The only time I get the American Spirit is during Davis Cup and I haven't gotten excited about Davis Cup since Sampras, Agassi, Courier were the main team.
Last year when Agassi played Federer at the USO Finals, I was routing for Agassi because I like Agassi, not because he's American. This year, I was routing for Federer because I'm not a big Roddick Fan and I really like records being broken, which raises the Bar up a notch again.