As a practice player on the U.S.'s 2007 Davis Cup team, John Isner (below) functioned as an apprentice who—when not hitting balls with his compatriots—was charged with learning from veterans like Andy Roddick. But after his gritty, five-set takedown of Roddick in the third round of the U.S. Open last Saturday, the 6'9", 24-year-old Isner proved he can hold his own on the big stage.
After missing two months this spring with mononucleosis, he reached the semifinals at the Legg Mason Classic in Washington, D.C., where he lost to Roddick. In avenging that loss last week, Isner not only brought to bear against Roddick his repertoire of booming serves, high-rpm ground strokes and soft hands at the net but also his improved conditioning. "I never panicked," says Isner. "Nobody expected me to win."