Absolutely astonishing!
"Returning home to Southern California, he entered into the first of six marriages in 1948 and though he had played little tennis in the previous years, Gonzalez soon began his climb up the amateur rankings.It was then that the unheralded Gonzalez exploded onto the elite scene, storming through the Forest Hills field as the 17th-ranked amateur player to score a 6-2, 6-3, 14-12 victory over South Africa's Eric Sturgess to capture the 1948 U.S. Nationals, which is the equivalent of the U.S. Open today. He was 20 years old and a Grand Slam champion.
"A year later, Gonzalez turned the final into a showcase for his fierce, fighting spirit. Facing a two-set deficit against top-seeded Ted Schroeder, 16-18, 2-6, 6-1, 6-2, 6-4 to successfully defend his championship. The victory gave Gonzalez the credibility to turn pro and play a long tour of 123 matches with the veteran world champion of tennis, Jack Kramer, who was then the world's best player.
At this point of his tennis career Gonzalez only had been playing for five years, not counting his years in the Navy, and lacked the extensive junior tournament experience of his rivals. . . ."