Unified cruiserweight world champion Gilberto Ramírez has laid down a challenge to Australian boxer Jai Opetaia following the Mexican's victory over British fighter Chris Billam-Smith in Riyadh, Saudi Arabia.

Ramírez comfortably outboxed a game Billam-Smith to move to a career record of 47-1 (30KOs) and add the Briton's WBO title to the WBA crown.

The 33-year-old's only defeat came against Dmitry Bivol at light heavyweight in 2022.

Ramírez won by unanimous decision, the judges scoring the fight 116-112, 116-112 and 115-113.

"Of course," Ramírez said when asked whether he would fight IBF and Ring champion Opetaia next.

"I want to unify with all the champions. That's the main goal for me."

The Mexican is no stranger to world title fights.

A former WBO super middleweight champion, Ramírez made five defences of his belt before moving up to light heavyweight, where he suffered the only defeat of his professional career, challenging then-champion Bivol for his WBA title.

Opetaia, 29, is widely considered the number-one cruiserweight in the world and is also on a path to unify the division.

First, the Australian has to face mandatory IBF challenger, likely number-one ranked German Hüseyin Cinkara (22-0). However he told BoxingScene he was ready to unify as soon as possible.

"We've got a mandatory after this one and then we'll get the unification fight, hopefully," Opetaia said earlier this week in an interview with BoxingScene.

"I don't care about the big build-ups and all this, just fight. 

"You already got a belt. I already got two belts. I've got the most string-pull out of all the cruiserweights. 

"I feel like everyone should be fighting for the Ring Magazine [title]. Whoever's got that is the top dog. I've got it. I've just gotta keep winning – these fights will come.

"I just want the belts. It's not like a personal vendetta towards one of these fighters – it's just if I'm not fighting for unification fights then I'm only maintaining what I have, and that's not what we want to do. 

"We don't want to maintain – we want to progress and move forwards."

Moving forwards could mean taking on some of boxing's biggest names in the near future, with undisputed light heavyweight champion Artur Beterbiev and Bivol both making noises that they might move up to the 90.6kg weight class in the future.

Then there is former two-weight undisputed champion Oleksandr Usyk, who suggested he too might come back down to the division in the near future.

"I think maybe after the rematch [against Tyson Fury], I am going to go down in weight to cruiserweight," unified heavyweight champion Usyk told the 3 Knockdown Rule podcast.

"I want more cruiserweight [fights].

"Maybe I can be undisputed for a second time in the cruiserweight division. It's my plan. 

"When I start to prepare for my training camp [for heavyweight fights], I have to eat all the time. For me it's hard. I don't like it." 

Usyk, who became undisputed at cruiserweight in 2018, beating Russian Murat Gassiev in Moscow, before moving up to heavyweight and becoming undisputed there by beating Fury in May 2024.

The Ukranian (22-0) has since vacated the IBF belt after he opted to take a rematch with Fury in December, promoting Daniel Dubois into that position.

German fighter Noel Mikaelian (27-2) holds the other WBC cruiserweight belt but is due to face his mandatory, Canadian Ryan Rozicki (20-1), should he beat number two-ranked Argentine Yamil Alberto Peralta (17-1) in early December.