Why to Watch: Spencer is a junior middleweight titleholder who is making her second defense, though she’s also stepping up in level of competition. And the last time Spencer did that, she lost.

Mayer, meanwhile, is stepping up in weight after winning world titles at junior lightweight and welterweight. While she is aiming to become a three-division titleholder, Mayer is also planning to return to 147lbs to fight for the undisputed championship.

Oh, and three world titles will be up for grabs.

Spencer, 10-2 (6 KOs), is the WBA junior middleweight titleholder — the vacant WBC and WBO titles will also be on the line given Cecilia Braekhus’ retirement. 

As an amateur, Spencer represented Canada in the 2012 Olympics, making it to the quarterfinal round of the middleweight tournament. She remained in the unpaid ranks for years after and is a late arrival to professional prizefighting; the 40-year-old only turned pro about four years ago.  That meant Spencer needed to be moved quickly. In June 2022, after nearly 10 months in the pros, she scored a first-round technical knockout of former titleholder Chris Namus. She did the same thing to former title challenger Cynthia Lozano that September. 

Spencer then took on the more experienced Femke Hermans, losing a unanimous decision in December 2022. Their rematch took place in October 2023 and had the vacant IBF belt on the line. Hermans won again, this time via majority decision. Spencer has won three fights since then. The second of them was a unanimous decision over the 7-2-1 Naomi Mannes in September 2024 for the WBA’s interim belt. Spencer was upgraded when primary titleholder Terri Harper vacated and moved down to lightweight. For Spencer’s first defense, she won a wide decision in April versus the 31-5-1 Ogleidis Suarez.

Spencer will be the naturally bigger fighter against Mayer, and she will have the home advantage at the Casino de Montreal in Montreal, Quebec, Canada. But Mayer, 21-2 (5 KOs), brings far more experience against upper-tier opposition.

Mayer, a 35-year-old who lives in Colorado Springs, competed in the 2016 Olympics. She turned pro in 2017, picked up a vacant world title in 2020 and unified a pair of belts in 2021. After losing via narrow split decision to Alycia Baumgardner in a 2022 fight for three world titles at 130, Mayer moved up in weight. She made one appearance apiece at lightweight and junior welterweight before arriving at welterweight in January 2024 and losing a split decision to then-IBF titleholder Natasha Jonas.

In her second welterweight title shot, however, Mayer unseated Sandy Ryan for the WBO belt via majority decision. That September 2024 battle was memorable for the leadup as well as the sensational action: An assailant threw a can of paint on Ryan as she left her hotel for the arena, leaving her visibly stunned. Mayer and Ryan had a rematch this past March, which Mayer won by unanimous decision.

The remaining three titles at 147lbs belong to Lauren Price.

“I couldn’t get the undisputed fight with Lauren Price, so rather than take an easy touch, I looked for the next best challenge,” Mayer said when this bout with Spencer was announced. “Beating Mary Spencer at 154lbs will make me a three-division world champion, and although I may be on the smaller side, I have the necessary skills and experience. I’ll dethrone Mary and then head back down to welterweight to challenge Price. I will be stronger, sharper, and better than ever.”

The undercard features several prospects at various stages of development. Super middleweight Wilkens Mathieu, 14-0 (10 KOs), will face Shakeel Phinn, 27-3-2 (17 KOs). Junior welterweight Arthur Biyarslanov, 19-0 (16 KOs), will take on Sergey Lipinets (18-4-1, 13 KOs).  Light heavyweight Mehmat Unal, 13-0 (11 KOs), will step in with Ralfs Vilcans, 18-2 (7 KOs). And welterweight Christopher Guerrero, 15-0 (9 KOs), will meet Williams Andres Herrera, 17-4 (7 KOs).

More Fights to Watch

Friday, October 31: Ivan Actis vs. Ariel Lopez (ESPN+ and ESPN Deportes)

The broadcast begins at 8 p.m. Eastern Time (midnight GMT).

This show in Cordoba, Argentina, features two of the country’s undefeated middleweights. 

Actis, 11-0-1 (7 KOs), is coming off a 10th-round knockout of the 5-1 Braian Matias Perez in June. 

Lopez, 7-0 (5 KOs), was last in the ring in November 2023, when he stopped the 5-9 Denis Alejandro Andrade in the seventh round.

Saturday, November 1: Joshua Buatsi vs. Zach Parker (DAZN)

The broadcast begins at 3:30 p.m. Eastern Time (7:30 p.m. GMT).

Joshua Buatsi, 19-1 (13 KOs), is a light heavyweight contender who is returning from his first professional defeat, a setback given how heavily featured he was in recent years.

The 32-year-old Buatsi was born in Ghana and grew up in London, England. He represented Team GB in the 2016 Olympics, taking home a bronze medal after losing in the semifinals to eventual silver medalist Adilbek Niyazymbetov. Buatsi signed with promoter Matchroom Boxing and was managed by Anthony Joshua.

Those relationships concluded, and Buatsi moved to promoter Boxxer. He won a unanimous decision against the undefeated Pawel Stepien in 2023, outpointed the 20-0 Dan Azeez in February 2024, and won the WBO’s interim light heavyweight belt in July 2024 with a split decision over Willy Hutchinson on the undercard of Joshua’s loss to Daniel Dubois.

That landed Buatsi on another big show this past February, when he faced former super middleweight champ Callum Smith on the undercard of Artur Beterbiev-Dmitry Bivol II. It was a prime spot but also a gamble, given that Buatsi’s interim belt put him in line for a shot at the winner, who at the time was the undisputed champion. 

The gamble didn’t pay off. Buatsi lost to Smith. It was a hard-fought battle, and Buatsi dug deep, but he also took plenty of punishment en route to dropping a unanimous decision. Buatsi has had about eight months to recover and work on improving himself. He’s also now changed promoters as a number of fighters left Boxxer; Buatsi is now signed with Queensberry Promotions.

There shouldn’t be any rush to put Buatsi in with Bivol (still the true king and lineal champ with three of the four major titles) or Beterbiev or even WBC beltholder David Benavidez just yet. Buatsi, who is ranked fifth by the WBC and sixth by the WBO, can test himself against Parker and then move on to his fellow ranked contenders, ensuring that he’s truly ready before facing the best light heavyweights in the world.

Zach Parker, 26-1 (18 KOs), is a 31-year-old from Woodville, England. He won his first 22 fights before facing John Ryder for the interim WBO super middleweight belt in November 2022. Parker hurt his right hand in the fourth round and decided not to continue on after the round concluded. 

Parker has won four bouts since while settling in as a light heavyweight. In March 2024, he outpointed the 27-1-1 Tyron Zeuge. That was followed by a fourth-round TKO of the 26-3 Jack Arnfield in July 2024. And in Parker’s last outing, he won a unanimous decision in February against the 21-1-2 Mickael Diallo. Parker is rated third at 175lbs by the WBO, 11th by the WBC, and 13th by the IBF and WBA.

More light heavyweights will clash on the undercard: Bradley Rea vs. Lyndon Arthur and Troy Jones vs. Liam Cameron.

Rea, 21-1 (10 KOs), is coming off a close unanimous decision win in June over the twice-beaten Shakan Pitters. Arthur is 24-3 (16 KOs), two of those defeats coming in his trilogy with Anthony Yarde, including a unanimous decision loss in their April rubber match. Arthur is 1-2 in his last three: the other loss came via shutout to Dmitry Bivol in late 2023, while the win was a split decision over Cameron in mid-2024.

Jones, 13-1 (6 KOs), is back for the second time since losing a unanimous decision to Ezra Taylor in May. Jones was originally scheduled to face Daniel Lapin, 12-0 (4 KOs), who pulled out in mid-September with an injury. Instead, Jones is facing Cameron, 23-7-1 (10 KOs), who is returning from his TKO2 loss to Ben Whittaker in their April rematch.

Saturday, November 1: Lenier Pero vs. Jordan Thompson (DAZN)

The broadcast begins at 8 p.m. Eastern Time (1 a.m. GMT).

Pero, 12-0 (8 KOs), is a 2016 Olympian who defeated Guido Vianello and then lost to Filip Hrgovic in the quarterfinals of the super heavyweight tournament. The 32-year-old Cuban now lives in Miami and has been fighting professionally since 2019. He remains in the developmental stages, though the WBA has ranked Pero third at heavyweight behind Moses Itauma and Michael Hunter. 

This will be Pero’s second fight of 2025. In April, he won a 10-round decision over the 9-4 Detrailous Webster. The victory over Webster took place at the Caribe Royale Orlando, which is where this fight with Thompson is also taking place.

Thompson, 15-1 (10 KOs), is a 32-year-old who lives in London, England. He is listed at 6-foot-6, an inch and a half taller than Pero. Somehow Thompson was long able to make cruiserweight with that frame. If his name is familiar, that’s because Thompson was stopped in four rounds by Jai Opetaia in September 2023. That was Thompson’s last outing, which means he’ll be returning from two years of inactivity.

The undercard includes a junior middleweight fight between Antraveous Ingram, 12-0 (6 KOs), and Yoelvis Gomez, 9-1 (7 KOs), as well as separate bouts featuring Matchroom Boxing prospects, all three of them Olympians: cruiserweight Pat Brown, 4-0 (4 KOs); junior middleweight Nishant Dev, 3-0 (2 KOs); and junior middleweight Omari Jones, 3-0 (3 KOs), who earned a bronze medal in 2024.

David Greisman, who has covered boxing since 2004, is on Twitter @FightingWords2. David’s book, “Fighting Words: The Heart and Heartbreak of Boxing,” is available on Amazon.