Answer
Brad Gilbert served as Andy Roddick's coach during his triumphant victory at the 2003 US Open, where Roddick claimed his maiden Grand Slam title. Gilbert, known for his strategic prowess and player development expertise, played a crucial role in guiding Roddick's game. His influence on Roddick's serve-and-volley style and mental resilience was instrumental in securing his breakthrough success at Flushing Meadows.