of the Miami challenger tournament. He then entered the Delray Beach tournament as a qualifier ranked world No. 244. He gained entrance to the main draw by defeating Nicolás Todero and Alex Bogomolov Jr. In the first round, he defeated Florian Mayer due to a retirement in the second set. In the second round, Nishikori defeated Amer Delić, another qualifier. In the quarterfinals, he won against Bobby Reynolds. In the semifinals, he upset Sam Querrey. In the final, Nishikori upset top seed James Blake in three sets to become the first Japanese man in nearly 16 years to win an ATP event. Nishikori lost in the first round of the Miami Masters to the Spanish player Albert Montañés. He faced James Blake again, this time at the River Oaks International tournament in Houston, Texas in the first round, but Kei lost in two sets. He went out in the third round of the 2008 Queen's Club Championships against Rafael Nadal in just over two hours. Facing the world No. 2, Nishikori played well in the match and showed promise. His first Grand Slam appearance at the 2008 Wimbledon Championships on 23 June 2008 ended in a first-round forfeiture to French player Marc Gicquel. Suffering from an abdominal muscle strain, Nishikori retired after the second set. In August, he entered the Beijing Olympics on a wildcard. There, he lost in the first round to Rainer Schüttler of Germany. Nishikori made his debut at the US Open, defeating 29th seeded Juan Mónaco in the first round. He cruised to the third round, after downing Croatian Roko Karanušić. On 30 August 2008, he became the first Japanese player to reach the round of 16 at the US Open in 71 years, when he beat fourth seed David Ferrer in five sets in what was considered one of the tournament's major upsets. He lost his chance, however, to compete in the quarterfinals when he was beaten by 17th seed Juan Martín del Potro in straight sets. In the Japan Open Tennis Championships, he made it to the round of 16, before losing to Frenchman Richard Gasquet. Nishikori was given a wildcard for the Stockholm Open, where he made it to his second ATP level semifinal of the year, despite playing with a knee injury. He received a walkover in his quarterfinal match against Mario Ančić, who had to withdraw due to illness. In the