Who was the first player to win a “boxed set” of Grand Slam titles (every possible title in singles, doubles, and mixed doubles)?
Don Budge was the first player to win a "boxed set" of Grand Slam titles, which means winning every possible title in singles, doubles, and mixed doubles. He achieved this feat in 1938, winning the Australian Open, French Open, Wimbledon, and the US Open in singles, as well as the men's doubles and mixed doubles titles at each tournament. Budge's remarkable achievement helped to establish him as one of the greatest tennis players of all time and a true legend of the sport.