Yes, upsets happen. They do frequently. But the truth is they're rarer in household events.
Take for instance, WTA 1000 events, a series of tournaments that largely host the best players in the world. Only 19 times in the previous 119 WTA 1000 events that have taken place has a player ranked 20th or lower made a run all the way to the championship.
Here's a look at the five lowest-ranked players to win:
Event: 2011 Toronto
Serena Williams was still on the front end of her comeback from a near-12 month stint on the sidelines with a foot injury, surgery for a blood clot in her lung and a pulmonary embolism that required emergency hospitalization. But it did not take long for Williams to move back up the rankings.
Her title run in Toronto came on the heels of a winning week at Stanford, which elevated her back into the Top 100. In Toronto, Williams defeated Alona Bondarenko, Julia Goerges, Zheng Jie, Lucie Safarova, fourth seed Victoria Azarenka and No.10 Samantha Stosur in the final.
The win was part of an 18-match win streak that summer, which ended a few weeks later at the hands of Stosur in the US Open final.
Event: 2021 Montreal
To win the biggest title of her career, Giorgi deployed her big-hitting baseline game alongside a strong defensive effort to win her first WTA 1000 title and third title overall. Montreal remains her only title above a WTA 250 level.
Giorgi defeated four seeds, with wins against No.9 seed Elise Mertens, Nadia Podoroska, No.7 seed Petra Kvitova, No.15 seed Coco Gauff, Jessica Pegula and No.4 seed Karolina Pliskova. The only player to get a set off the Italian was Pegula in the semifinals. The win vaulted Giorgi back into the Top 40 for the first time since June 2019.
Event: 2019 Indian Wells
Just 18 at the time, Andreescu had yet to crack the Top 100 to start the 2019 season. Less than three months later, she would foreshadow what was to come in her breakout season, beginning with her memorable run to her first Hologic WTA Tour title.
Granted a main-draw wild card after winning the WTA 125K event at Newport Beach a month earlier -- she defeated Pegula in the final -- Andreescu defeated Irina Camelia Begu, Dominika Cibulkova and Stefanie Voegele to make the Round of 16.
From there, she knocked off four Top 20 players in Wang Qiang and Garbiñe Muguruza, then No.6 Elina Svitolina and No.8 Angelique Kerber in back-to-back three-set nail-biters to become the youngest Indian Wells champion since Serena Williams in 1999.
Event: 2020 Cincinnati
Azarenka came through the unique circumstances that surrounded the 2020 Western & Southern Open, which was held in New York at the Billie Jean King USTA National Tennis Center because of COVID. Ranked No.59, Azarenka had not won a match in 12 months, carrying a four-match losing streak into the tournament.
Along the way to the final, she defeated Donna Vekic, Caroline Garcia, Alizé Cornet, Ons Jabeur and Johanna Konta, losing only a single set during the week. Set to face Naomi Osaka in the final, Azarenka would take home the trophy via walkover after Osaka withdrew with a hamstring injury.
A few weeks later, the two would meet in the US Open final, where Osaka rallied from a set down to win 1-6, 6-3, 6-3.
Ranking: No. 45
Event: 2019 Dubai
When Bencic gets hot, she can slice through a draw like a hot knife. She had already done it once during her stunning run to her first WTA 1000 title as an 18-year-old, defeating four of the Top 5 seeds to win Toronto in 2015.
But Bencic was ranked No.20 in Toronto. Flash forward four years and Bencic was working her way back after enduring a series of injuries in 2017 and falling out of the Top 300. But with her ranking back in the Top 50 heading into Dubai, Bencic caught fire.
After wins against Lucie Hradecka and Stefanie Voegele to open the tournament, Bencic proceeded to knock off four consecutive three-set wins over Top 10 players. To win her first title since 2015, Bencic saved six match points to oust No.9 Aryna Sabalenka and then defeated No.2 Simona Halep, No.6 Elina Svitolina and, ultimately, No.4 Petra Kvitova in the final.