Despite her growing reputation as an elite-level player, Gibson was effectively barred from entering the premier American tournament, the United States National Championships (now the US Open) at Forest Hills. While USTA rules officially prohibited racial or ethnic discrimination, players qualified for the Nationals by accumulating points at sanctioned tournaments, most of which were held at white-only clubs. In 1950, in response to intense lobbying by ATA officials and retired champion Alice Marble—who published a scathing open letter in the magazine "American Lawn Tennis"—Gibson became the first Black player to receive an invitation to the Nationals, where she made her Forest Hills debut a few days after her 23rd birthday. Although she lost narrowly in the second round in a rain-delayed, three-set match to Louise Brough, the reigning Wimbledon champion and former US National winner, her participation received extensive national and international coverage. "No Negro player, man or woman, has ever set foot on one of these courts," wrote journalist Lester Rodney at the time. "In many ways, it is even a tougher personal Jim Crow-busting assignment than was Jackie Robinson's when he first stepped out of the Brooklyn Dodgers dugout."