ARLINGTON, Texas – Errol Spence Jr. could laugh about his mouthpiece mishap afterward.

During the sixth round, however, losing his mouthpiece in a second straight fight was no laughing matter early Sunday morning. Spence’s “rookie” reaction to Ugas’ right hand dislodging his mouthpiece could’ve cost the unbeaten welterweight champion his IBF and WBC belts because it enabled Ugas to hit him with a left-right combination that rocked Spence and knocked him into the ropes.

Referee Laurence Cole called for Spence and Ugas to stop fighting and appeared as if he were going to step between them to allow Spence to reinsert his mouthpiece. Cole instead stepped back, which permitted Ugas to take two shots at Spence while his guard was down.

That sequence barely a minute into the sixth round seemingly inspired Spence to put on a show for an announced crowd of 39,946 that assembled at AT&T Stadium mostly to support Spence. The strong southpaw proceeded to pick apart Ugas with a variety of power punches, completely closed the area around his right eye and won by 10th-round technical knockout.

Spence (28-0, 22 KOs) could’ve criticized Cole, but the undefeated, unified champion chose to accept complete blame for failing to protect himself at all times. The DeSoto, Texas, native also acknowledged that he needs to do a better job of keeping his mouthpiece secured when asked about it during his post-fight press conference.

“Hey, nah, you on point,” a laughing Spence said. “You right. Nah, I just gotta get a new mouthpiece. My mouthpiece been messed up. I gotta get a new mouthpiece. It’s like it’s not holding to my mouth at all. So, it’s flopping everywhere and so, I gotta bite down real hard for it to stay in my mouth. So, it’s my fault. It’s a rookie mistake for me.

“And that was a rookie mistake for me, too, like looking off and looking for my mouthpiece and then, you know, I get punched like three times. So, you know, that was my fault, too, because you’re supposed to protect yourself at all times. So, you know, I ain’t mad.”

Energized by his hometown crowd, Spence landed left uppercuts and straight lefts with regularity, which did a lot of damage to the area surrounding Ugas’ right eye.

A Texas Department of Licensing and Regulation doctor determined during the 10th round that Ugas shouldn’t continue. Ugas (27-5, 12 KOs), who protested the stoppage, couldn’t see out of his severely swollen right eye.

An X-ray taken at a nearby hospital early Sunday morning detected a fractured right orbital bone, which will keep the 35-year-old, Cuban-born boxer out of the ring for an extended period of time.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.