Nonito Donaire is on the cusp of becoming one of the oldest world champions at 40.

This Saturday night (Sunday in Manila), Donaire and Alejandro Santiago of Mexico slug it out for the vacant World Boxing Council bantamweight title.

The scheduled 12-rounder will be on the undercard of the world welterweight war starring Terence Crawford and Errol Spence at the T-Mobile Arena in Las Vegas.

During an open media workout yesterday, Donaire displayed flashes of his old fiery form to cement his standing as the — 190 betting favorite ($190 wins $100).

Santiago, known for his puzzling style and durability, is pegged at +160 ($100 wins $160).

If victorious, it will be Donaire's third reign as WBC champion after winning it for the first time in 2011 and reigning once again in 2021.

Winner of four world titles in as many weight classes, Donaire is best regarded as the most accomplished Filipino fighter next to Manny Pacquiao.

Against Santiago, Donaire, a professional since February 2001, will be parading a 42-7 record with 28 knockouts.

Santiago is best remembered by Filipino fight fans as the crafty boxer who almost dethroned Jerwin Ancajas in their 2018 world title fight in Oakland.