CARSON, Calif. – Gary Antuanne Russell was extended deeper than at any point in his career, though still untested in his latest victory.

The undefeated prospect had his way with Puerto Rico’s Jovanie Santiago, forcing a stoppage after six rounds in their junior welterweight contest Saturday evening at Dignity Health Sports Park in Carson, California.

Santiago was dropped in round four and battered throughout, with the fight stopped in between rounds six and seven.

Russell looked to make up for lost time right from the opening bell, having not fought since last February. The 2016 U.S. Olympian took the fight directly to Santiago, who aimed to prove that his strong performance versus Adrien Broner just three months ago was not a fluke.

Within seconds, it was clear that Santiago was in with a high-octane opponent who, unlike Broner, is not hesitant to let his hands go. Russell—the younger brother of WBC featherweight titlist Gary Russell Jr.—was sharp with his right jab and straight left hand out of the southpaw stance. Santiago was unable to contend with the difference in hand speed, other than to clinch once on the inside.

Russell pumped his jab throughout round two, while also taking his attack to the body. Santiago was stopped in his tracks from a body shot, though eventually pushing past the blow to offer a right hand. Russell continued his relentless pursuit of his Boricua foe, landing a crisp left hand in the closing seconds of the round.

Santiago provided his best infighting skills in round three, offering head movement inside. Russell was able to get his timing down, connecting with a vicious left uppercut. Santiago took the shot to the best of his ability but was beginning to wear down.

Russell exploded in round four, catching Santiago with a blinding right hook early in the frame. Santiago managed to beat the count of referee Sharon Sands but spend the rest of the round on the defensive. Russell was dangerously active, in pursuit of continuing his run of early exits only for Santiago to make it to the bell.

The bell sounded to begin round five, marking uncharted territory for Russell in his young career. Santiago couldn’t do anything with it, fighting through a cut alongside his left eye and unable to defend against Russell’s straight left hand. Russell continued to mix in right hooks to the body, often dropping a left hand over the top immediately after.

Russell had Santiago in trouble midway through round six, landing a flurry of power punches along the ropes. Santiago weathered the storm, only to have to clinch his way out of trouble following an ensuing volley. Russell stalked the Puerto Rican only for the bell to sound.

Santiago barely made it to his stool before the fight was waved off, suffering his second straight defeat as he falls to 14-2-1 (10KOs).

Russell advances to 14-0 (14KOs), having yet to go to the scorecards as a pro.

Russell-Santiago served as the opening bout of a Showtime tripleheader. Headlining the show, Nordine Oubaali (17-0, 12KOs) defends his WBC bantamweight title versus former four-division champ Nonito Donaire (40-6, 26KOs).

Jake Donovan is a senior writer for Twitter: @JakeNDaBox