Following twelve forgettable rounds, Monroe got the decision 118-110, 117-111 and 116-112 to pick up a fringe version of the WBO title.
Also on the Dallas bill, NABF featherweight champion Joseph Diaz Jr. got the better of a bloodied Andrew Cancio to finally force the stoppage in the ninth round, whilst Diego De La Hoya cruised through what looked his toughest test on paper with a decisive ten-round triumph over Luis Orlando Del Valle.
The 22 year-old went through a couple a gears in the fight but never looked in trouble on his way to a 100-90, 99-91 twice win on the cards.
Welterweight contender Sadam Ali bounced back from his first defeat to Jessie Vargas in March to convincingly out-point Saul Corral and improve to 23-1.
Prior to Ali’s win, lightweight Hector Tanajara scored a decision over Thomas Smith to maintain his perfect record, whilst Vergil Ortiz knocked out Ernesto Hernandez in the first session at super-lightweight for a second pro win.
In the early contests, British light-heavyweight Anthony Yarde scored a first round stoppage of Rayford Johnson on his US debut, whilst 118-pounder Joshua Franco also carded a TKO in four against Bryan Bazan as both remained undefeated.
Over eight and six rounds respectively, super-lightweight Zachary Ochoa and super-welterweight Alexis Salazar improved their records with decision victories.