Yes one biracial African-american tennis player is James Blake who is half white half black. A plain African-American tennis male is Donald Young.
Roger Federer and Serena Williams
No professional male tennis player has ever publicly come out of the closet. Not that there haven't been gay male tennis players.
Roger Federrer, Rafael Nadal, Andy Roddick,
So many, Pete Sampras, Andre Agassi
Andy Roddick is the highest ranked American. He is #5 overall. The next is Sam Querry and then James Blake.