1938 through 1947. He lost his first match in 1938 in straight sets, winning only two games. At the 1939 U.S. Championships he was beaten in the second round by 11th-seeded and fellow Californian Joe Hunt. In 1940 Kramer defeated fourth-seeded Frank Parker in a five-sets quarterfinal but lost to second-seeded and eventual champion Don McNeill in the semifinal. At the 1941 Championships he was seeded for the first time, at No. 11, and reached the quarterfinal where third-seeded Frank Kovacs proved too strong. In 1942, Kramer won the men's singles in the Ojai Tennis Tournament. Kramer received a leave from his duties in the Coast Guard to compete at the 1943 Championships. Seeded second, he reached the final, despite being weakened by food poisoning, but lost it to Joe Hunt in four sets. During World War II he continued to win prizes in the United States, since the war had effectively put an end to international tennis, but did not compete in the U.S. Championships in 1944 and 1945. The first Grand Slam tournament Kramer entered after the war was the 1946 Wimbledon Championships where he was seeded second but was upset in by Jaroslav Drobný in a five-set fourth round match. At the 1946 U.S. Championships he was seeded third but managed to win his first Major singles title after a straight-set victory in the final against Tom Brown, losing just a single set in the tournament. He was ranked World No. 1 amateur in 1946 by Pierre Gillou, Harry Hopman and Ned Potter. At the 1947 Wimbledon Championships Kramer was seeded first and justified it by winning the title after another straight-sets win against Brown in a final that lasted only 48 minutes. At 1947 U.S. Championships number one seed Kramer faced Frank Parker in the final. Parker won the first two sets as Kramer struggled to find form. Then, Kramer "changed suddenly from a stumbling novice to a raging perfectionist" and went on to win in five sets to retain his title. Kramer was ranked World No. 1 amateur in 1947 by John Olliff, Pierre Gillou and Ned Potter. Kramer made his debut for the US Davis Cup team in 1939 in the final of the World Group against Australia. Together with Joe Hunt they lost the doubles match against John Bromwich and Adrian Quist. In 1946 and 1947 he was part of the winning US