Answer
The answer is Younes El Aynaoui. Roddick and El Aynaoui faced off in the quarterfinals of the 2003 Australian Open, engaging in a grueling five-set match that lasted an astonishing five hours and three minutes. This marathon encounter stands as the longest match of Roddick's professional tennis career. It was a remarkable display of endurance and determination from both players, showcasing their exceptional athleticism and mental fortitude.