The Latest on the U.S. Open tennis tournament (all times local):

6 p.m.

Canadian teenager Bianca Andreescu has upset Serena Williams 6-3, 7-5 in the U.S. Open final for her first Grand Slam title.

Andreescu's victory Saturday prevented Williams from claiming what would have been her record-tying 24th major singles championship.

This is the second year in a row that Williams has lost in the U.S. Open final.

She 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 19-year-old Andreescu is the first woman to win the trophy at Flushing Meadows in her tournament debut in the Open era, which began in 1968 when professionals were allowed to enter the majors.

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5:05 p.m.

Bianca Andreescu has won the first set 6-3 against Serena Williams in the U.S. Open final.

The 19-year-old Andreescu broke Williams' serve in the first and last games of the set — with Williams double-faulting on break point both times.

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4:40 p.m.

Serena Williams playing in the U.S. Open women's final inspired a performer to change the lyrics to "America The Beautiful" — and the crowd loved it.

Adrienne Warren sang "And crown thy good with 'sisterhood,'" when the actual lyric to the line is "brotherhood."

Williams and her older sister, Venus, have combined to win eight U.S. Open singles titles, playing each other in back-to-back years in 2001 and 2002.

Meghan, the Duchess of Sussex, is attending the final against Bianca Andreescu and sitting in Williams' box. Williams and the former Meghan Markle are friends, and Williams and her husband attended her wedding to Prince Harry.

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4:15 p.m.

The U.S. Open women's final is underway, with Serena Williams trying to win a record-tying 24th Grand Slam singles title. She faces 19-year-old Bianca Andreescu, who is trying to become the first Canadian woman to win one.

The eighth-seeded Williams has reached three major finals since having a baby but lost them all. Two were at Wimbledon and the other last year at the U.S. Open against Naomi Osaka, which quickly devolved after Williams argued with chair umpire Carlos Ramos about a warning over receiving coaching signals.

If she wins this championship, 20 years after she won her first of six titles at Flushing Meadows, the 37-year-old Williams would equal Margaret Court's record for most Grand Slam titles.

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2:45 p.m.

Bethanie Mattek-Sands and Jamie Murray have successfully defended their U.S. Open mixed doubles championships.

Mattek-Sands and Murray beat the top-seeded team of Hao-Ching Chan and Michael Venus 6-2,-6-3. They are the first team to defend a U.S. Open mixed doubles title since Kevin Curren and Anne Smith in 1981 and 1982. Murray became the first man in the Open era to win three straight mixed doubles titles in Flushing Meadows after starting the run in 2017 with Martina Hingis.

Murray won his fifth Grand Slam mixed doubles title and Mattek-Sands won her third.

Later Saturday, Serena Williams seeks a record-tying 24th Grand Slam singles title when she faces 19-year-old Canadian Bianca Andreescu.

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3 a.m.

Serena Williams lost her temper and then lost the match when she played for last year's U.S. Open championship.

She gets another chance Saturday night, again seeking a record-tying 24th Grand Slam singles title when she faces 19-year-old Canadian Bianca Andreescu.

The 37-year-old Williams has lost all three major finals she has reached since returning from giving birth, including to Naomi Osaka in Flushing Meadows last year. That match is best remembered for Williams' arguments with chair umpire Carlos Ramos.

She remains one behind Margaret Court's record for most Grand Slam trophies and seeks her seventh at the U.S. Open, 20 years after winning her first.

Andreescu, 33-4 this season, can become the first Canadian woman to win a Grand Slam title.