First Grand Slam
Starting off strong in 1990 Sampras made it to the fourth round of the Australian Open in January and earned his first professional victory in February at the U.S. Pro Indoors in Philadelphia. Knocked out in the first round of his first Wimbledon, he entered the U.S. Open seeded twelfth. Riding on the strength of his over-whelming serve, Sampras walked through the early rounds. He then beat Ivan Lendl in five sets in the quarterfinals, four-time Open winner John McEnroe in the semifinals, and met Andre Agassi in the finals.
Sampras's matchup with Agassi proved to be a contrast in styles. Sampras, who modeled his behavior after an early generation of tennis greats including Laver, was subdued in his behavior, dress, and demeanor, which compared sharply with Agassi's long hair, nontraditional (nonwhite) clothing, and open personality. Agassi, however, could do little to hold up against his opponent's serve, and Sampras won in three sets, 6-4, 6-3, 6-2, becoming the youngest U.S. Open winner in history (19 years, 28 days).
Sampras followed up his 1990 U.S. Open victory by winning the first Grand Slam Cup, an event that features the 16 best finishers in the year's Grand Slam events. With numerous endorsement contracts added to his on-court earnings, Sampras netted approximately $6.5 million in 1990. During 1991, suffering under the pressure of overly high expectations as well as some physical injuries, Sampras skipped the Australian Open and was eliminated in the second round of both Wimbledon and the French Open. In his attempt to defend his U.S. Open title, he was eliminated in the quarterfinals.