Natasha Jonas overcame a tough test against Mikaela Mayer to retain her IBF welterweight title with a split-decision victory Saturday night at M&S Bank Arena in Liverpool, England. Two judges scored the fight for Jonas 96-94 and 96-95, and the third for Mayer 97-93.
Jonas (15-2-1, 9 KOs) is a two-division champion and in 2012 she became the first British woman to participate in boxing at the Olympic Games in London.
Every round between Jonas and Mayer was close, with Jonas starting faster and landing the more effective shots, including punishing body punches. Mayer (19-2, 5 KOs), a former junior lightweight champion making her welterweight debut, took over the fight in the last few rounds, busting Jonas' left eye and backing her up with powerful right hands.
"I know she is going to be absolutely devastated with the result because I've been there," Jonas, who had a controversial split draw against Terri Harper in 2020 and lost a close decision to Katie Taylor in 2021, said after the fight. "It feels like the world is over. She is on my top two people that I've fought. She is very skilled. Her time will come again. She beat a lot of the champions."
Mayer believed she did enough to win and asked for a rematch, which, she said, is deserved.
"I landed the cleaner shots," Mayer said. "I think that this fight is worth seeing again. Like she said, it was one of the toughest fights she's had. I didn't have a rematch clause on my side, but I'm hoping we can get this fight done again."
Jonas moves up three places and takes the No. 6 spot from Mayer, who drops to No. 8.
Here's the current top 10.
Note: Results are through Jan. 25.
1. CLARESSA SHIELDS 
Previous ranking: No. 1
RECORD: 14-0, 2 KOs
DIVISION: Middleweight undisputed champion
LAST FIGHT: W (UD10) Maricela Cornejo, June 3
NEXT FIGHT: TBA
2. KATIE TAYLOR Previous ranking: No. 3
RECORD: 23-1, 6 KOs
DIVISION: Junior welterweight undisputed champion and lightweight unified champion
LAST FIGHT: W (MD10) Chantelle Cameron, Nov. 25
NEXT FIGHT: TBA
3. AMANDA SERRANO Previous ranking: No. 2
RECORD: 46-2-1, 30 KOs
DIVISION: Featherweight unified champion
LAST FIGHT: W (UD12) Danila Ramos, Oct. 27
NEXT FIGHT: March 2 vs. Nina Meinke
4. CHANTELLE CAMERON Previous ranking: No. 4
RECORD: 18-1, 8 KOs
DIVISION: Junior welterweight
LAST FIGHT: L (MD10) Katie Taylor, Nov. 25
NEXT FIGHT: TBA
5. SENIESA ESTRADA Previous ranking: No. 5
RECORD: 26-0, 9 KOs
DIVISION: Strawweight unified champion
LAST FIGHT: W (UD10) Yokasta Valle, March 29
NEXT FIGHT: TBA
6. NATASHA JONAS 
Previous ranking: No. 9
RECORD: 15-2-1, 9 KOs
DIVISION: Welterweight champion
LAST FIGHT: W (SD10) Mikaela Mayer, Jan. 20
NEXT FIGHT: TBA
7. SAVANNAH MARSHALL Previous ranking: No. 7
RECORD: 13-1, 10 KOs
DIVISION: Super middleweight unified champion
LAST FIGHT: W (MD10) Franchon Crews Dezurn, July 1
NEXT FIGHT: TBA
8. MIKAELA MAYER 
Previous ranking: No. 6
RECORD: 19-2, 5 KOs
DIVISION: Welterweight
LAST FIGHT: L (SD10) Natasha Jonas, Jan. 20
NEXT FIGHT: TBA
9. JESSICA MCCASKILL Previous ranking: No. 8
RECORD: 12-3-1, 5 KOs
DIVISION: Welterweight unified champion
LAST FIGHT: DRAW (SD10) Sandy Ryan, Sept. 23
NEXT FIGHT: TBA
10. DELFINE PERSOON Previous ranking: No. 10
RECORD: 49-3, 19 KOs
DIVISION: Junior lightweight
LAST FIGHT: W (UD6) Agustina Marisa Belen Rojas, Nov. 1
NEXT FIGHT: TBA
The formula
The rankings are based on a descending points system, with a first-place vote receiving 10 points, a second-place vote receiving nine points and so on.
Others receiving votes: Yokasta Valle (4), Franchon Crews Dezurn (2), Hyun Choi (1)
How our experts voted
Nick Parkinson: 1. Shields, 2. Taylor, 3. Serrano, 4. Cameron, 5. Jonas, 6. Estrada, 7. Mayer, 8. Marshall, 9. McCaskill, 10. Crews-Dezurn
Salvador Rodriguez: 1. Taylor, 2. Shields, 3. Serrano, 4. Estrada, 5. Cameron, 6. Marshall, 7. Jonas, 8. McCaskill, 9. Mayer, 10. Valle
Bernardo Pilatti: 1. Shields, 2. Taylor, 3. Serrano, 4. Cameron, 5. Marshall, 6. Jonas, 7. McCaskill, 8. Mayer, 9. Estrada, 10. Crews-Dezurn
Charlie Moynihan: 1. Shields, 2. Serrano, 3. 3. Taylor, 4. Estrada, 5. Jonas, 6. Mayer, 7. Cameron, 8. Persoon, 9. Marshall, 10. Choi
Claudia Trejos: 1. Shield, 2. Serrano, 3. Taylor, 4. Cameron, 5. Marshall, 6. Jonas, 7. Persoon, 8. Mayer, 9. Estrada, 10. McCaskill
Damian Delgado Averhoff: 1. Shields, 2. Taylor, 3. Serrano, 4. Cameron, 5. Estrada, 6. Marshall, 7. Jonas, 8. Valle, 9. Persoon, 10. Mayer
Andrew Feldman: 1. Shields, 2. Taylor, 3. Serrano, 4. Estrada, 5. Cameron, 6. Marshall, 7. Jonas, 8. McCaskill, 9. Mayer, 10. Persoon
ESPN experts' poll
First place: Shields (6), Taylor (1)
Second place: Taylor (4), Serrano (2), Shields (1)
Third place: Serrano (5), Taylor (2)
Fourth place: Cameron (4), Estrada (3)
Fifth place: Cameron (2), Marshall (2), Jonas (2), Estrada (1)
Sixth place: Marshall (3), Jonas (2), Estrada (1), Mayer (1)
Seventh place: Jonas (3), Cameron (1), Mayer (1), Mcaskill (1), Persoon (1)
Eighth place: Mayer (2), McCaskill (2), Marshall (1), Persoon (1), Valle (1)
Ninth place: Estrada (2), Mayer (2), Marshall (1), McCaskill (1), Persoon (1)
10th place: Crews-Dezurn (2), Mayer (1), McCaskill (1), Persoons (1), Valle (1), Choi (1)