The IBF’s latest ratings update – released May 12 – includes the installation of one new No. 1 contender and one curious addition.

Both of those are in the same weight class:

At junior middleweight: The first and second spots had been vacant. But May 10 brought a title elimination bout, with Erickson Lubin (previously No. 3) stopping Ardreal Holmes Jnr (previously No. 6) to claim the No. 1 spot. Holmes fell to No. 11.

Meanwhile, the previously unranked Conor Benn entered the IBF’s ratings at No. 5 after his unanimous decision loss in last month’s war with Chris Eubank Jnr, which took place at middleweight, not at 154lbs. Benn came in at 156.4lbs for the Eubank fight, and his previous two bouts had been at junior middleweight.

There was one other notable entry and one departure: Josh Kelly, who had been ranked sixth at 160lbs, is now rated fourth at 154lbs. And Tim Tszyu, previously in the eighth position, is now out of the IBF’s ratings due to his upcoming rematch with WBC titleholder Sebastian Fundora.

The IBF’s titleholders and No. 1 contenders in each weight class are:

Heavyweight: Daniel Dubois has the IBF world title; the No. 1 slot is vacant. Dubois is scheduled to face lineal/WBA/WBC/WBO champion in a rematch for the undisputed championship on July 19.

Cruiserweight: Jai Opetaia has the world title; Huseyin Cinkara is his No. 1 contender.

Light heavyweight: Dmitry Bivol has the IBF, WBA and WBO world titles. Michael Eifert is the IBF’s No. 1 contender. Bivol and Artur Beterbiev are expected to fight their rubber match later this year.

Super middleweight: Saul “Canelo” Alvarez has all four world titles; the No. 1 slot is vacant. Alvarez is scheduled to face Terence Crawford on September 12.

Middleweight: Janibek Alimkhanuly has the IBF and WBO world titles; the IBF’s No. 1 slot is vacant.

Junior middleweight: Bakhram Murtazaliev has the world title; Erickson Lubin is his No. 1 contender.

Welterweight: Jaron Ennis has the IBF and WBA world titles; Lewis Crocker is the IBF’s No. 1 contender

Junior welterweight: Richardson Hitchins has the world title; Subriel Matias is his No. 1 contender.

Lightweight: Vasiliy Lomachenko has the world title; Raymond Muratalla is the interim titleholder and therefore is Lomachenko’s mandatory challenger; the No. 1 slot is vacant.

Junior lightweight: The world title is vacant; Eduardo Nunez (No. 1) and Masanori Rikiishi (No. 3) are scheduled to fight May 28 for the vacant title.

Featherweight: Angelo Leo has the world title; Tomoki Kameda is the No. 1 contender. Leo and Kameda are scheduled to fight on May 24.

Junior featherweight: Naoya Inoue has all four world titles; Sam Goodman is the IBF’s No. 1 contender.

Bantamweight: Ryosuke Nishida has the world title; the No. 1 slot is vacant

Junior bantamweight: The world title is vacant, as is the No. 1 slot.

Flyweight: Masamichi Yabuki has the world title; Felix Alvarado is the No. 1 contender.

Junior flyweight: is the IBF’s No. 1 contender; Christian Araneta is the No. 1 contender.

Minimumweight: Pedro Taduran has the world title; the No. 1 slot is vacant.

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.