A year after "fighting for her life" and undergoing four surgeries after giving birth to daughter Olympia, Serena Williams was defeated 6-2, 6-4 in maybe the most controversial final ever.
Then early in the second set, Williams was given a code violation for coaching by Ramos after her coach Patrick Mouratoglou appeared to make a gesture to her.
She was then docked a point for a second violation when she smashed her racquet after dropping serve at 3-3.
In 2011, she was called for hindrance by yelling during a point and had a raging tantrum.
"If I'm honest I was coaching, I don't think she looked at me", Mouratoglou told ESPN.
The game penalty put Osaka 5-3 up and she kept her cool to pull off a historic win.
"I know everyone was cheering for her and I'm sorry it had to end like this", said Osaka. For me to say "thief" and for him to take a game, it made me feel like it was a sexist remark.
"I had an opportunity to do that this summer, and it didn't happen, so I'm just going to keep trying", said Williams.
"For me, it blows my mind". And they're going to be allowed to do that because of today.
Osaka spent the formative years of her childhood living in NY and first came to Flushing Meadows as a fan hoping to catch a glimpse of Williams.More news: IPhone XS: The Latest On Apple's Upcoming Phones
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"I love you, Serena", she added before adding "I love you, mom; I love everybody".
"But I was, like 100 percent of the coaches in 100 percent of the matches so we have to stop this hypocritical thing". I want to clarify myself what he's talking about. Honestly, there's a lot I can learn from her from this match.
She ended up losing 6-2, 6-4 to Osaka, marking the 20-year-old's first grand slam win.
Williams overwhelmed Anastasija Sevastova 6-3 6-0 to reach her 31st grand slam singles final. "Since I already know she's a good player, I don't want to be surprised if she plays better or not".
Mouratoglou admitted in a postgame interview that he was indeed coaching Serena from the coaches box, but also said she probably wasn't aware he was doing so. "I don't really see what would change". For a moment, there was a question on whether she would continue playing.
But Williams will represent the stiffest test yet for Osaka after also cruising mostly unchallenged into the final, her only real blip coming in the fourth round when she needed three sets to get by Estonian Kaia Kanepi. "She deserved credit, she deserved to win". It's on the commercials, it's everywhere.
"When I step onto the court, I feel like a different person". Every time I step out on this court, I am so grateful I have an opportunity to play this sport.
Williams has dropped only one set in the tournament and, although she was similarly dominant in getting to the Wimbledon final only to lose heavily to Angelique Kerber, she looks to have moved up several notches.
Despite the age and experience difference - Osaka is 16 years Williams' junior - it was the American who opened the match looking the more nervous. She represents perhaps the next generation of great women tennis players who will try to fill the void left by Serena when she leaves competitive tennis.