Australian Open champion Madison Keys loses in the US Open's first round to Renata Zarazua of Mexico

NEW YORK (AP) — Pretty much from the get-go at the U.S. Open on Monday, Madison Keys could tell she wasn't hitting the ball well or feeling very much at all like the self-confident player who claimed her first Grand Slam title at the Australian Open in January. After 89 unforced errors, including 14 double-faults, the No. 6-seeded Keys was gone from Flushing Meadows in the first round with a 6-7 (10), 7-6 (3), 7-5 loss to 82nd-ranked Renata Zarazua of Mexico. "For the first time in a while ... my nerves really got the better of me, and it kind of became a little bit paralyzing," said Keys, the runner-up in New York to good friend Sloane Stephens in 2017 and a semifinalist in 2018 and 2023. "I felt like I was just slow. I wasn't seeing things the way that I wanted to, which I feel like resulted in a lot of bad decisions and lazy footwork." Her first U.S. Open with the status of major champion — thanks to defeating No. 1 Aryna Sabalenka in the final at Melbourne Park — was over just as it began. "You always kind of feel first-round jitters and, as the day is getting closer, feeling a little bit more and more nervous," said Keys, who played with her left thigh heavily taped. "But I feel like, for whatever reason, today I just couldn't separate myself from ... feeling like winning matters just way too much." She made so many mistakes off the spin-laden shots coming her way that Zarazua needed to produce just eight winners to earn the biggest victory of her career. Zarazua lost in the first or second round of all eight of her previous Slam appearances. Yet somehow, it was Zarazua who managed to deal with any nervousness better, even though she was competing in cavernous Arthur Ashe Stadium for the first time and had only had a chance to hit there once a couple of days prior. The 5-foot-3 Zarazua came into the day with a 0-6 record against opponents ranked in the top 10. "I'm a little bit small in height, so coming in here, it was like: 'Oh, my God. This is huge,'" Zarazua said about the largest stadium in tennis, which holds nearly 24,000 spectators. When the match ended with Keys missing a forehand, Zarazua smiled as wide as possible, held her racket atop her head, then placed a hand over her face. This one certainly was memorable, in part because it did not come easily and lasted 3 hours, 10 minutes. Zarazua trailed by a set — after frittering away five chances to take the opener — and 3-0 in the second. Quite a daunting deficit. But she never went away. "Kudos to her for making me play a lot of balls today," Keys said. "I mean, she's a tricky player." While Keys was one of 25 American players in the women's singles draw, the 27-year-old Zarazua is Mexico's lone entrant in the bracket. She moved to San Antonio as a teen, and is now based in Florida. "In Mexico, yeah, it's probably not the most famous sport," Zarazua said about tennis, which she picked up after starting out in gymnastics and diving. "I got into tennis," she explained, "just because my brother was playing, and he was like, 'I think this is a bit safer sport.'" What else happened at the US Open on Monday? Brazilian teenager João Fonseca, who turned 19 on Thursday, won his U.S. Open debut, defeating Miomir Kecmanovic 7-6 (3), 7-6 (5), 6-3 in front of a raucous crowd of his countrymen. Another precocious player, 18-year-old Canadian Vicky Mboko, who was seeded 22nd, was eliminated by two-time major champion Barbora Krejcikova 6-3, 6-2. Two-time Wimbledon champion Petra Kvitova, who is 35, played her last match before retirement, losing to Diane Parry 6-1, 6-0, and 2022 U.S. Open semifinalist Caroline Garcia, 31, also exited the final tournament of her career, eliminated 6-4, 4-6, 6-3 by Kamilla Rakhimova. Frances Tiafoe, a two-time semifinalist in New York, beat Yoshihito Nishioka in straight sets. Venus Williams and Carlos Alcaraz were scheduled to be on court at night. Who is on Tuesday's schedule at the US Open? A packed program for Day 3 of the first round includes Grand Slam champions Coco Gauff, Iga Swiatek and Jannik Sinner. Gauff's opponent is Ajla Tomljanovic, who beat Serena Williams at the U.S. Open in the last match of 23-time major title winner's career. This is Gauff's first match since she began working with biomechanics coach Gavin MacMillan in a bid to improve her serve.