Madison Keys, the American tennis star ranked No. 6 in the world, is out after her first-round matchup at the 2025 U.S. Open did not go her way.Keys was upset by Renata Zaraza, an unranked competitor from Mexico, 7-6 (12-10), 6-7 (3-7), 7-5, as the crowd was stunned at Arthur Ashe Stadium in New York.Keys was looking to finish strong after winning the Australian Open earlier this year to collect a Grand Slam title. But Zaraza was relentless despite losing a hard-fought first set in a thrilling tiebreak.CLICK HERE FOR MORE SPORTS COVERAGE ON FOXNEWS.COMKeys was able to take the first set following her 12-10 victory in the tiebreak, but Zaraza forced another in the second and came away with the 7-3 win to keep the match alive.Then, in the third set, Zaraza shockingly broke Keys to make it 6-5, and she put her away in the next game to seal the stunning win.WORLD NO. 1-RANKED ARYNA SABALENKA NARROWLY AVOIDS MAJOR UPSET, ADVANCES TO WIMBLEDON SEMIFINALFor Keys, the loss could be explained by a rare plethora of unforced errors. She made a whopping 89 unforced errors compared to 46 winners, and no matter what youre ranked in the seeding, that is going to be hard to overcome.Thus, an American who was expected to be competing well into the U.S. Open on home soil is heading home early.Fourth-ranked Jessica Pegula, the daughter of Buffalo Bills and Buffalo Sabres owner Terry Pegula, dominated in her opening round matchup against Mayar Sherif of Egypt, while Emma Navarro (No. 10) defeated Yafan Wang of China in straight sets as well.No. 3-ranked Coco Gauff, who is the highest-ranked American in the world, is set for her first-round match against Australias Ajla Tomljanovic on Tuesday night.Follow Fox News Digitalssports coverage on X, and subscribe tothe Fox News Sports Huddle newsletter.