Nineteen-year-old Bianca Andreescu defeated Serena Williams in two sets at the U.S. Open's Final Saturday. Andreescu is the first Canadian — man or woman — to win a major single's championship.

Williams didn't go down without a fight: after being down 5-1, in the second set, she rallied to win the next four games. But it wasn't enough to take down Andreescu, who won the next two games and win the set 7-5.

In the final of the Canadian Open last month, Andreescu won after Williams retired with an injury in the first set. The match is best remembered for Andreescu — who hadn't yet been born the first time Williams won the U.S. Open in 1999 — consoling the top player of this generation and letting Williams know just how much of an influence she has been, CBS Sports reports.

Bianca Andreescu of Canada celebrates winning match point during her Women's Singles final match against against Serena Williams of the United States on day thirteen of the 2019 US Open at the USTA Billie Jean King National Tennis Center on September 07, 2019 in the Queens borough of New York City. Al Bello / Getty Images

This is the second year in a row that Williams has lost in the final at Flushing Meadows. This one had none of the controversy of 2018, when she got into an extended argument with the chair umpire while being beaten by Naomi Osaka.

Get Breaking News Delivered to Your Inbox

Williams has now been the runner-up at four of the seven majors she has entered since returning to the tour after having a baby two years ago. The 37-year-old American remains stuck on 23 Grand Slam singles title, one shy of Margaret Court's mark for the most in history.

Andreescu went up 5-1 in the second set and served for the victory there, even holding a match point at 40-30. But Williams erased that with a forehand return winner off a 105 mph serve.

That launched a four-game run for Williams, who broke Andreescu again to make it 5-all. The Arthur Ashe Stadium crowd was overwhelmingly supporting Williams, not surprisingly, and spectators got so loud as she tried to put together a successful comeback that Andreescu covered her ears with her hands after one point.

Suddenly, this was a contest.

Or so it seemed.

But as well as Andreescu handled everything - herself, her far-more-experienced and successful opponent, and even the moment - Williams was far from her best, especially while serving. She got broken for the sixth time in the final game.

Serena Williams of the United States reacts during her Women's Singles final match against Bianca Andreescu of Canada on day thirteen of the 2019 US Open at the USTA Billie Jean King National Tennis Center on September 07, 2019. Emilee Chinn / Getty Images

The 19-year-old Andreescu is the first woman to win the trophy at Flushing Meadows in her main-draw tournament debut in the Open era, which started in 1968 when professionals were allowed into Grand Slam tournaments. She only has participated in four majors in her brief career.

Just think: A year ago, Andreescu was losing in the opening round of qualifying.

On Saturday, there she was, putting her hands on her head, dropping her racket and then pumping her fists when it ended. After a hug from a smiling Williams at the net, Andreescu kissed the blue court and rolled onto her back, soaking in the applause.