Lightweight undisputed champion Katie Taylor regained the No. 1 spot in ESPN's pound-for-pound rankings with an impressive unanimous decision victory over Natasha Jonas on May 1.
Taylor, a previous No. 1, was leapfrogged by Claressa Shields, a two-time Olympic gold medalist and now two-division undisputed champion, back in March, after Shields dominated Marie-Eve Dicaire in a 10-round unanimous decision victory to unify all four major junior middleweight belts. Shields also became the undisputed middleweight champion with a decision victory over Christina Hammer in 2019. She's the first fighter, female or male, to be undisputed champion in two different divisions in the modern era.
Boxing TV presenter and founder of Behind The Gloves, Michelle Joy Phelps, moved Taylor to the No. 1 spot after her victory over Jonas, saying that to this point, Taylor has defeated stronger competition than Shields.
"My decision to move Taylor back to the No. 1 spot is simple: opposition. She continuously dominates at lightweight and proved yet again against Jonas what a talent she is," Phelps said. "Taylor delivers exciting fights against opponents who continue to challenge her, making her better with each passing fight. After the Jonas fight, Taylor told me she'd love a rematch with Jessica McCaskill and/or a fight with Amanda Serrano as she's open to fighting again at 140 or making a catchweight if it means making the right fights happen.
ESPN's Kel Dansby said it was a tough decision, but decided to keep Shields at No. 1 based on the way Shields competes.
"Shields remains in the top spot over Taylor by the thinnest of margins in my list, but it's hard to ignore the eye test," said Dansby. "Taylor is an amazing champion, but this is now three straight fights that could've gone for her or her opponent. She's extremely entertaining but she isn't dominating her competition. Shields is not only a dual-division undisputed champion, but she is blowing away her opponents in these fights. She barely has competitive rounds, let alone fights."
So, who else is in the ESPN.com women's pound-for-pound rankings? Here's the list.
Note: Results are through May 10.
1. KATIE TAYLOR 
Previous ranking: No. 2
RECORD: 18-0, 6 KOs
DIVISION: Lightweight (undisputed champion)
LAST FIGHT: W (UD10) Natasha Jonas, May 1
NEXT FIGHT: Sept. 4 vs. Jennifer Han
2. CLARESSA SHIELDS 
Previous ranking: No. 1
RECORD: 11-0, 2 KOs
DIVISION: Junior middleweight and middleweight undisputed champion
LAST FIGHT: W (UD10) Marie Eve Dicaire, March 5
NEXT FIGHT: TBA
3. AMANDA SERRANO Previous ranking: No. 4
RECORD: 41-1-1, 30 KOs
DIVISION: Featherweight (titlist)
LAST FIGHT: W (UD10) Yamileth Mercado, Aug. 29
NEXT FIGHT: TBA
4. JESSICA MCCASKILL Previous ranking: No. 3
RECORD: 10-2, 3 KOs
DIVISION: Welterweight undisputed champion
LAST FIGHT: W (UD10) Cecilia Braekhus, March 13
NEXT FIGHT: TBA
5. DELFINE PERSOON 
Previous ranking: No. 5
RECORD: 45-3, 18 KOs
DIVISION: Lightweight
LAST FIGHT: W (UD10) Elena Gradinar, July 3
NEXT FIGHT: Nov. 1 vs. TBA
6. MIKAELA MAYER Previous ranking: No. 7
RECORD: 15-0, 5 KOs
DIVISION: Junior lightweight (titlist)
LAST FIGHT: W (UD10) Erica Farias, June 19
NEXT FIGHT: TBA
7. CHRISTINA HAMMER Previous ranking: No. 6
RECORD: 26-1, 12 KOs
DIVISION: Middleweight
LAST FIGHT: W (KO7) Sanna Turunen, Dec. 20
NEXT FIGHT: TBA
8. CECILIA BRAEKHUS Previous ranking: No. 8
RECORD: 36-2, 9 KOs
DIVISION: Welterweight
LAST FIGHT: L (UD10) Jessica McCaskill, March 13
NEXT FIGHT: TBA
9. TERRI HARPER Previous ranking: 10
RECORD: 11-0-1, 6 KOs
DIVISION: Junior lightweight (titlist)
LAST FIGHT: W (TKO9) Katharina Thanderz, Nov. 14
NEXT FIGHT: TBA
10. HYUN CHOI Previous ranking: No. N/R
RECORD: 18-0-1, 4 KOs
DIVISION: Junior lightweight (titlist)
LAST FIGHT: W (UD10) Calista Silgado, Dec. 18
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: Layla McCarter (5), Savannah Marshall (5), Seniesa Estrada (4), Yesica Bopp (3), Yulihan Luna (2), Yamileth Mercado (2), Daniela Bermudez (1), Chantelle Cameron (1).
How our experts voted
Timothy Bradley Jr.: 1. Shields, 2. Taylor, 3. Serrano, 4. McCaskil, 5. Hammer, 6. Mayer, 7. Harper, 8. Estrada, 9. Braekhus, 10. Persoon
Nick Parkinson: 1. Taylor, 2. Shields, 3. Serrano, 4. McCaskill, 5. Braekhus, 6. Persoon, 7. Hammer, 8. Mayer, 9. Bopp, 10. Cameron
Michelle Joy Phelps: 1. Taylor, 2. Shields, 3. McCaskill, 4. Serrano, 5. Mayer, 6. Braekhus, 7. Harper, 8. Persoon, 9. Marshall, 10. Choi
Salvador Rodriguez: 1. Taylor, 2. Shields, 3. McCaskill, 4. Serrano, 5. Persoon, 6. Harper, 7. Mayer, 8. Braekhus, 9. Luna, 10. Estrada
Bernardo Pilatti: 1. Taylor, 2. Shields, 3. Serrano, 4. McCaskill, 5. Hammer, 6. McCarter, 7. Persoon, 8. Mayer, 9. Mercado, 10. Bermudez
Charlie Moynihan: 1. Shields, 2. Taylor, 3. Serrano, 4. McCaskill, 5. Hammer, 6. Choi, 7. Persoon, 8. Mayer, 9. Braekhus, 10. Bopp
Kel Dansby: 1. Shields, 2. Taylor, 3. Serrano, 4. McCaskill, 5. Persoon, 6. Hammer, 7. Mayer, 8. Marshall, 9. Harper, 10. Braekhus
ESPN experts' poll
First place: Taylor (4), Shields (3)
Second place: Shields (4), Taylor (3)
Third place: Serrano (5), McCaskill (2)
Fourth place: McCaskill (5), Serrano (2)
Fifth place: Hammer (3), Persoon (2), Braekhus (1), Mayer (1)
Sixth place: Persoon (1), Mayer (1), Hammer (1), Braekhus (1), Harper (1), Choi(1), Bermudez (1)
Seventh place: Persoon (2), Mayer (2), Harper (2), Hammer (1)
Eighth place: Mayer (3), Persoon (1), Braekhus (1), Marshall (1), Estrada (1)
Ninth place: Braekhus (2), Harper (1), Marshall (1), Mercado (1), Luna (1), Bopp (1)
10th place: Persoon (1), Braekhus (1), Choi (1), Bermudez (1), Estrada (1), Cameron (1), Bopp (1)