By the time Nonito Donaire climbs the ring in Japan next month for what could very well be his last world title crack, he would already be a ripe 43-year-old.

Donaire turned another leaf Sunday, a month before his showdown with Seiya Tsutsumi for the World Boxing Association (WBA) bantamweight crown at the Ryogoku Kokugikan Sumo Arena in Tokyo.

On paper, it looks as if Donaire has no business being in the ring.

Oddsmakers have installed Tsutsumi a -300 favorite while Donaire a +200 underdog.

Those in favor of Tsutsumi have to shell out $300 to win $100 while those who pick Donaire stand to collect double since a mere $100 wager wins $200.

Tsutsumi, making the second defense of the WBA 118-pound strap, has a 12-0-3 win-loss-draw record with eight knockouts.

In one of his leadup fights to a world title opportunity, Tsutsumi beat Kazuki Anaguchi for the Japan bantamweight championship at the Ariake Arena in Tokyo in December 2023.

The bout went the full route and Anaguchi later collapsed and was brought to the hospital for emergency surgery to remove a blood clot on his brain.

Six weeks later, he was dead.

Donaire, a four-division world champion, sports a 43-8-0 mark with 28 knockouts.

In his last fight, he defeated Andres Campos of Chile five months ago in Buenos Aires, Argentina, making Donaire a title candidate since that particular fight was billed as a clash for the interim throne as Tsutsumi was recovering from injury.

If victorious, Donaire will become one of boxing’s oldest world champions.

But the odds are stacked heavily against his bold bid to upset Tsutsumi, who is a lot fresher and will be fighting on home soil.

Still, Donaire has proven many times that he could come up with a big performance when the odds are not on his side.

In his first duel with Naoya Inoue in November 2019, Donaire lost by unanimous decision in what was a very tough and intense battle.

However, in the rematch, Inoue easily disposed of the Filipino-American puncher in just two rounds in June 2022.

Currently, Donaire is in Cebu City getting ready at the well-equipped Omega Boxing Gym.