It was a day of all kinds of firsts for Bianca Andreescu, who won her first US Open, became the first-ever Grand Slam singles winner from Canada and was the first major champion born in the 2000s. And she did it the hard way, defeating Serena Williams, 6-3, 7-5, in an electrically excited Arthur Ashe Stadium.

All of this was, obviously, a big deal, and social media reacted accordingly. Andreescu was congratulated by her fellow players ...

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The Toronto sports teams, including the reigning NBA champion Raptors ...

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Canada's athletes ...

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Tennis' legends ...

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Tennis Channel's analysts ...

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And Andreescu's many fans, among them being Chrissy Teigen and Canadian Prime Minister Justin Trudeau:

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Of course, the match was a momentous occasion for Serena, too, and her efforts definitely did not go unnoticed:

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Another year of Grand Slams on the women's side is in the books, and 2019 has seen two recurring champions and two new faces break through. It's safe to say Andreescu, 19, has plenty more major moments ahead of her.