The U.S. Open women’s finals Saturday at Arthur Ashe Stadium, the USTA Billie Jean King National Tennis Center in Flushing Meadows-Corona Park, Queens, didn’t end how the 23-time major champion Serena Williams hoped or envisioned.

Her impeccable play leading up to the finals versus Naomi Osaka—in six matches before Saturday Williams dropped only one set—was overshadowed by her uncharacteristically unsteady serve and ineffective forehand against Osaka. The 36-year-old, six-time U.S. Open winner lost to the 20-year-old Osaka, who idolized Williams as a little girl and dreamed of facing her in a major final, 6-2, 6-4 as Osaka captured her first major title in her first appearance in a major championship match.

More than Williams’ skills betraying her, it was her battle with chair umpire Carlos Ramos that turned the afternoon into a bittersweet affair for the players, tournament officials and vociferous fans in attendance. The confrontation began when Ramos issued a code violation to Williams in the second game of the second set, asserting she was receiving coaching from Patrick Mouratoglou. Williams’ coach admitted to giving her hand signals from the stands. It is a common practice among coaches and is rarely cited, especially in a major final.

Williams was adamant she was not paying attention to Mouratoglou, who was located in the stands. After the coaching violation, Williams earned a point penalty for cracking her racket with the score 3-2 in the second set. Angry for being penalized for coaching, Williams complained to Ramos, “You stole a point from me and you are a thief” and “I’d rather lose than cheat.” He subsequently disciplined her for verbal abuse, a full game penalty that pushed Williams to the brink of defeat with Osaka then serving for the match at 5-3.

Williams called for the tournament referee Brian Earley and supervisor Donna Kelso, but her lobbying efforts failed to change the outcome. During one of her exchanges with Ramos, Williams accused the umpire of sexism.

“There are men out here that do a lot worse,” she maintained, “but because I’m a woman, you’re going to take this away from me? That is not right.”

What was unquestionably taken away was the joy from Osaka. The daughter of a Haitian father and Japanese mother, Osaka, who was born in Japan and moved to the United States with her parents when she was three, was clearly shaken and heartbroken by the crowd booing during the post-match trophy ceremony, tears welling up in her eyes. The fans’ ire was directed at Ramos, but it tainted what should have been Osaka’s moment. Later, she still expressed undying affection for Williams.

“I’m always going to remember the Serena that I love,” Osaka said. “It doesn’t change anything for me. She was really nice to me, like, at the net and on the podium. I don’t really see what would change.”

Earlier, Williams shared mutual sentiments. “She played an amazing match,” she said of Osaka. “She deserved credit. She deserved to win.”

Conversely, she did not have a positive opinion of Ramos. “I’ve seen other men call other umpires several things,” Williams noted. “I’m here fighting for women’s rights and for women’s equality and for all kinds of stuff. For me to say ‘thief’ and for him to take a game, it made me feel like it was a sexist remark.”

Williams said the controversial afternoon could serve as life instruction for her 1-year-old daughter Alexis in the years to come.

“I’ll tell her, first of all, if she sees it, that I stood up for what’s right,” said Williams. “Sometimes things in life don’t happen the way we want them, but to always stay gracious and stay humble. I think that’s the lesson we can all learn from this, just like I did.”