Marcos Andres Giron (born July 24, 1993; ) is an American professional tennis player. He achieved a career-high singles ranking of No. 49 on 16 May 2022 and a doubles ranking of No. 194 on August 1, 2022. He won the boys' singles in the Ojai Tennis Tournament in 2009 and the men’s invitational in 2011. In 2014, Giron won the singles title at the 2014 NCAA Division I Tennis Championships for UCLA. Professional career 2020: First US Open win & top 100 debut Giron reached the second round of a major at the 2020 US Open where he won his first match against Marc Polmans in five sets and at the French Open for the first time in his career. In November, Giron recorded his first top-ten win against seventh seed Matteo Berrettini at the Paris Masters. 2021: Major third round, Olympics & top 60 debuts Giron started his 2021 season at the Murray River Open, an event that was organized as a lead-up tournament to the Australian Open due to other tournaments in Australia being cancelled as a result from the COVID-19 pandemic. He beat 10th seed, Adrian Mannarino, in the second round. He lost in the third round to eighth seed and eventual champion, Dan Evans. He participated in the main draw as a direct entry at the Australian Open for a second consecutive year. He lost in the first round to sixth seed and world No. 7, Alexander Zverev, in four sets. At the Open Sud de France, Giron was defeated in the first round by qualifier Tallon Griekspoor. Getting past qualifying at the Rotterdam Open, he was eliminated in the first round by fourth seed, world No. 8, and eventual champion, Andrey Rublev. In June, Giron reached the third round of a major at the French Open for the first time in his career. At Halle, Giron reached his first quarterfinal at an ATP 500 level tournament as a qualifier where he was defeated by Félix Auger-Aliassime. As a result of this good run, he reached a then career-high of No. 65 on June 21, 2021. Giron made the second round at the Olympics, beating Norbert Gombos before losing to Kei Nishikori in three sets. In September at the Sofia Open, Giron reached his fourth quarterfinal of the season (with quarterfinal appearances in Halle, Metz and Winston-Salem) after defeating third seed Alex de Minaur in