Kid Galahad and Terri Harper surrendered their world titles in big upset losses on the same card Saturday in England.
Veteran Kiko Martinez became a two-weight world champion at the age of 35 after a huge knockout of Galahad in the sixth round of their IBF featherweight title fight.
Unheralded American Alycia Baumgardner, meanwhile, stopped Harper -- No. 7 in ESPN's women's pound-for-pound rankings -- in the fourth round to win the WBC and IBO super featherweight titles at Sheffield Arena.
Both English boxers lost fights that they were expected to win in order to set up bigger fights next year.
After serving an 18-month ban for a doping violation, and then winning a world title at the second attempt after losing a split decision to Yorkshire rival Josh Warrington in 2019, Galahad's career had been gaining momentum.
Martinez, a former world junior featherweight champion in 2013-14, hardly arrived with a formidable record on British soil. The Spaniard suffered his seventh loss in the United Kingdom earlier this year and was not expected to give Galahad any problems.
Galahad (28-2, 17 KOs), 31, looked like he was going to make it an early night when he shook Martinez with a right hand in the opening round.
Galahad, who won the vacant title against James Dickens in August, cleverly found openings to land more punches. Martinez could not cover up in time as Galahad proved too quick and too smart in the opening rounds.
Martinez (43-10-2, 30 KOs), 35, from Alicante, was caught by a straight left in the third round and was cut above his right eye.
At the start of the fifth round, Martinez came charging off his stool to take the fight to the champion.
Galahad seemed to lose focus and momentum, became complacent, and paid for dropping his hands when Martinez floored him with a huge right hand. Galahad got up at the count of eight and was saved by the bell.
But Galahad's head did not clear and he was knocked out cold with the first punch of the sixth round when Martinez landed another overhand right.
"For the last three years I have been living like a monk," Martinez said. "My wife has helped me a lot with my anxiety and it has paid off. I'm in better shape than I was at the age of 20 years old."
Galahad, who needed two attempts to make weight for the fight, is likely to be offered a rematch against Martinez.
Baumgardner announces herself on world stage, upsets Harper
On the undercard, Baumgardner landed a thunderous overhand right in the fourth round to stop Harper and win the WBC women's world junior lightweight title.
Harper, who was making her third title defense after a year out of action and surgery for a hand injury, lost the belt after being blown away by Baumgardner.
It was a big shock, as Harper started the fight at No. 7 in ESPN's pound-for-pound rankings with hopes of setting up a big fight against a rival world champion in 2022.
But Baumgardner, known as "The Bomb," detonated a huge right hand early in the fourth round after she had dominated the fight from the opening bell.
"I dreamed of this moment," Baumgardner said. "I looked in the mirror every day and told myself you're going to be world champion. ... I know a lot of people haven't seen me and I've not had the platform to show I can punch."
The 27-year-old Baumgardner (11-1, 7 KOs), from Bingham Farms, Michigan, had never fought for a world title after turning professional in 2017 but oozed confidence from the start, holding her hands low and flicking out the jab in the opening round.
The Detroit boxer was even better in the second round and stunned Harper with a right hand before unloading a quick combination. Harper could not respond with anything as she struggled with Baumgardner's change of pace.
Harper (11-1-1, 6 KOs), 25, from Doncaster, continued to struggle in the third round and was then stopped on her feet early in the fourth.
Baumgardner landed an overhand right which immediately stiffened Harper's legs, and the champion suddenly became a sitting target. Before Baumgardner could land another punch, referee Mark Lyson made a good stoppage 23 seconds into the fourth round.
Harper had been linked to a title unification fight against WBO champion Mikaela Mayer (16-0, 5 KOs) or WBA champion Hyun Mi Choi (19-0-1, 5 KOs). She now must consider whether to take a rematch with Baumgardner after such a heavy defeat.
Matchroom promoter Eddie Hearn confirmed there was a rematch clause.
"It was a big defeat for Terri, and it was a big statement from Alycia," Hearn said.
Also on the undercard, England's Chris Billam-Smith (14-1, 10 KOs) retained the European cruiserweight title with a unanimous points win over France's Dylan Bregeon.
Billam-Smith, 31, won the belt via a split decision over Northern Ireland's Tommy McCarthy last summer. The Bournemouth fighter defeated Bregeon (11-2-1, 3 KOs), 27, from Nantes, in more convincing style and with a strong finish. He won on all cards -- 120-109, 119-109, 119-109.