Entertainment Sports Coco Gauff Upsets Naomi Osaka as Serena Williams Falls in 3rd Round of Australian Open 15-year-old Coco Gauff defeated the reigning Australian Open champion in two sets, while Serena Williams lost to No. 27 seed Wang Qiang By Dave Quinn Dave Quinn Instagram Twitter Dave Quinn is an Editor for PEOPLE, working across a number of verticals including the Entertainment, Lifestyle and News teams. People Editorial Guidelines Published on January 24, 2020 11:33 AM Share Tweet Pin Email Photo: TPN/Getty; Juergen Hasenkopf/Shutterstock Two of tennis' biggest stars are out of the 2020 Australian Open. Naomi Osaka, the Australian Open's reigning women's champion from Japan, and Serena Williams — a 23-time major champ fresh off her victory at the ASB Classic in Auckland, New Zealand — both lost in the third round of tennis matches on Friday. Their defeats at Melbourne Park were two of the biggest Open upsets. Osaka, 22, was bested by American newcomer Coco Gauff, who, at 15, became the youngest player to eliminate a reigning champ in the professional era, ESPN reported. She triumphed over Osaka 6-3, 6-4. Prior to that, in the bracket's same quarter, Williams, 38, lost to Wang Qiang 6-4, 6-7 (2), 7-5, according to the outlet. Wang, who is 10 years Williams' junior, at 28 years old, is ranked as the No. 27 seed. Serena Williams Wins First Title Since Welcoming Daughter, Donates Prize Money to Wildfire Relief Serena Williams. Jason Heidrich/Icon Sportswire via Getty Naomi Osaka. Hannah Peters/Getty Coco Gauff and Naomi Osaka Will Face Off 5 Months After Emotional U.S. Open Match Both Osaka and Williams were disappointed after their setbacks. "You don't want to lose to a 15-year-old, you know?" Osaka said in her post-game interview. "Her serve is way better. I feel like I wasn't really swinging freely, and she was." As for Williams, she said the loss — which ends her quest for a 24th Grand Slam title — took her by surprise. "[Entering the third set] I was optimistic I would be able to win," Williams told the press following the match. "I thought, 'Okay, now finish this off.' I honestly didn't think I was going to lose that match." "She served well. I didn't return like Serena," she added. "Honestly, if we were just honest with ourselves, it's all on my shoulders. I lost that match. I can't play like that. I literally can't do that again. It's unprofessional. It's not cool. So it is what it is." Serena Williams Refuses to Answer Question About Pal Meghan Markle — But Tells Reporter, 'Good Try' Coco Gauff. Kelly Defina/Getty Coco Gauff 'Can't Thank' Naomi Osaka 'Enough' for Including Her in Interview After U.S. Open Loss Back in September, Gauff was previously defeated by Osaka in the third round of the U.S. Open. After that defeat, Osaka famously consoled a crying Gauff and included her in her post-win interview. "I wanted to leave the court because I lost," Gauff laughed while looking back at the moment during an appearance on Today that same month. "And [Osaka] was like 'No, come with me' and I was just shocked because no one ever does that." She explained that while she knew Osaka, they weren't close at the time. "Obviously now we talk a lot more because of that moment," she revealed. "I couldn't thank her enough and I was really shocked. It was an emotional moment — good and bad emotions." But the young tennis star showed off different emotions after her win against Osaka on Friday. "Honestly, like, what is my life? Like, oh, my gosh!" Gauff told the crowd during her on-court interview. "Two years ago, I lost first round in juniors, and now I'm here. This is crazy." The teenager also joked about wanting to take "a selfie for Instagram" with 11-time major champion Rod Laver. Caroline Wozniacki. Clive Brunskill/Getty Meanwhile, Osaka and Williams weren't the only previous Australian Open champs to fall Friday. Caroline Wozniacki, a 2018 winner, was defeated by Ons Jabeur in her third-round match. She lost 7-5, 3-6, 7-5, ESPN reported. The loss was especially hard for the athlete as it was her last match as a professional tennis player. "The farewell I got today was absolutely incredible! Watching this video still gives me goose bumps! Thank you everyone for all the love and support over the years! Excited for what the future holds!❤️" the tennis star wrote on Instagram following the match. Back in December,Wozniacki told PEOPLE that she would retire after the Australian Open, to focus on her health and her family. "I've thought about it for a long time," she said in the exclusive interview. "It's obviously not an easy decision, and I don't think it ever would be. Tennis is something that I've done for my entire life, and I wake up and I practice and I play tournaments, but there's so many other things out there that I'd love to do." She continued on to explain her love of the Australian Open, the tournament where she won her first grand slam title. "I love it there," she said. "The support there for me has always been amazing." In 2018, Wozniacki was diagnosed with rheumatoid arthritis. She joked through tears about the condition in her Friday post-game interview, per ESPN, and said, "I think it was only fitting that my last match ended with a forehand error." Ons Jabeur will now face off against Qiang in the next match.Gauff's next opponent will be 21-year-old American Sofia Kenin.