Jaime Munguia forever leaves behind the 154-pound division as he sets his sights on the world's best middleweights.

The first order of business at the new weight for the former junior middleweight titlist is a 12-round clash with Gary 'Spike' O'Sullivan, which headlines from The Alamodome in San Antonio, Texas (Saturday, DAZN, 9:00pm ET; preliminary card beginning at 7:00pm ET).

Both boxers remained disciplined enough through the holiday season to do their job at the scale. Tijuana's Munguia (34-0, 27KOs) weighed 159.4 pounds, as did Ireland's O'Sullivan (30-3, 21KOs).

Munguia made five successful defenses of the junior middleweight title, the entirety of his six-fight reign taking place in a 16-month clip beginning with a one-sided knockout of Sadam Ali to win the crown in May 2018.

The final fight of his title reign came last September, stopping Ghana's Patrick Allotey in four rounds before opting later in the year to move up in weight.

O'Sullivan has won two straight since a 1st round knockout loss to former middleweight titlist David Lemieux in September 2017.

The evening's chief support pits unified super middleweight titlist Franchon Crews-Dazurn (6-1, 2KOs) in a 10-round title defense versus former heavyweight titlist Alejandra 'La Tigra' Jimenez (12-0-1, 9KOs).

Crews-Dazurn—whose lone career loss came to unbeaten pound-for-pound queen Claressa Shields when both made their respective pro debuts—weighed in right at the 168-pound limit. Jimenez—who weighed 236.5 pounds for her heavyweight title win in 2017—tipped the scales at a fight-ready 164.6 pounds.

Also on the main portion of the DAZN livestream:

-       San Antonio’s own Hector Tanajara (18-0, 5KOs) weighed 134.6 pounds for a scheduled 10-round lightweight clash versus Tijuana’s Juan Carlos Burgos (33-3-2, 21KOs), a former title challenger who weighed 134.4 pounds;

-       Joshua Franco (15-1-2, 7KOs)—who also hails from San Antonio—checked in at 114.8 pounds for a scheduled 10-round junior bantamweight bout versus Guadalajara’s Jose Alejandro Burgos (17-2, 14KOs) who weighed 114.2 pounds.

FULL WEIGHTS

Jaime Munguia 159.4 vs. Gary 'Spike' O'Sullivan 159.4—12 rds, middleweight

Franchon Crews-Dezurn 168 vs. Alejandra Jimenez 164.6—10 rds, super middleweight

Hector Tanajara 134.6 vs. Juan Carlos Burgos 134.4–10 rds, lightweight

Joshua Franco 114.8 vs. Jose Alejandro Burgos 114.2–10 rds, junior bantamweight

Travell Mazion 153.4 vs. Fernando Castaneda 159.2—10 rds, junior middleweight

Hector Valdez 121.4 vs. Luis Alberto Rios 122—8 rds, junior featherweight

Angel Fierro 134.4 vs. Alex Martin 138.2—8 rds, lightweight

James Wilkins 129.4 vs. James Early 128.8—6 rds, junior lightweight

George Rincon 139.6 vs. Diego Vicente Perez 139.8—6 rds, junior welterweight

Tristan Kalkreuth 184.2 vs. Blake LaCaze 181.8—4 rds, light heavyweight

Jake Donovan is a senior writer for BoxingScene.com. Twitter: @JakeNDaBox