Michel Rivera preserved his perfect record despite fighting two divisions above his most effective weight.

The unbeaten lightweight prospect from Miami by way of Santo Domingo, Dominican Republic stopped Puerto Rico’s Anthony Mercado in the eighth round of their FS1- televised headliner Saturday evening at Shrine Auditorium & Expo Hall in Los Angeles.

Rivera scored three knockdowns on the night, the last of which prompted an immediate stoppage from referee Edward Collantes at 2:26 of round eight.

Rivera weighed a career-heaviest 144 ½ pounds for this bout, though not at all discouraged by the extra weight as he thoroughly dominated Mercado over the course of their eight-round affair. Mercado suffered the first of three knockdowns on the night in round two, though a questionable call as he tripped over Rivera’s left foot seconds after the unbeaten Dominican prospect connected with a right hand. Referee Edward Collantes merely saw the punch land and not the aftermath, thus issuing a mandatory eight count.

Time was called in round three after Rivera landed a left hook well below the beltline as Mercado limped away in pain. Rivera kept it clean the rest of the way, more than doubling up in landed punches and offering a healthy mix of aggression and clean boxing.

Mercado took a knee early in round six after getting clipped upstairs. Rivera remained patient, boxing the rest of the way while looking to set up an emphatic finish.

Mercado tried to make a fight of it in the eighth and final round, coming forward but not landing anything of consequence. Rivera connected with a right hand which buzzed Mercado in the final minute, with a subsequent volley forcing Mercado to the canvas at which point the fight was stopped.

Rivera advances to 20-0 (13KOs) with the win, though a return to lightweight in his immediate future. Mercado falls to (13-5, 11KOs) with the defeat, snapping a two-fight win streak.

Opening the telecast, Anthony Cuba (1-0-1, 1KO) was held to a four-round draw versus Diego Elizondo (3-2-3, 0KOs). Cuba won 39-37 on one card, overruled by matching scores of 38-38 in their entertaining lightweight bout.

Both bouts aired ahead of the Premier Boxing Champions (PBC) on Fox tripleheader, headlined by former two-time super middleweight titlist Anthony Dirrell (33-2-1, 24KOs) in a 12-round semifinal eliminator versus Kyrone Davis (15-2, 6KOs).

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