ALLENTOWN, Pennsylvania – Martino Jules entered the ring Saturday night with just one knockout win in his first eight professional fights.

The undefeated junior lightweight didn’t even need a full round to add to that total in front of his hometown fans. The Allentown native knocked down overmatched Mexican Pablo Cupul twice before Ricky Gonzalez jumped in to spare Cupul any more punishment.

Gonzalez stopped their scheduled four-rounder 2:39 into the first round on the Gary Russell Jr.-Tugstsogt Nyambayar undercard at PPL Center.

The 22-year-old Jules (9-0, 2 KOs) first floored Cupul with a straight left hand. Cupul got up and continued, but Jules eventually overwhelmed him with a barrage of power punches that left Cupul crumpled on the canvas in a neutral corner.

The 32-year-old Cupul (10-31, 5 KOs) has been knocked out in four straight bouts and has lost five consecutive fights overall.

Earlier Saturday night, Jose Marrufo aggressively went after Gary Antuanne Russell as soon as their eight-round lightweight fight started.

About two minutes later, Marrufo was flat on his back, apparently unaware of what hit him. The unbeaten Russell, one of WBC featherweight champion Gary Russell Jr.’s younger brothers, nailed Marrufo with a counter right hook that ended their fight just 2:12 into it.

Marrufo tried to get up, but referee Ricky Gonzalez quickly determined that Marrufo was in no condition to continue.

Russell, a 23-year-old southpaw, has now knocked out each of his 13 pro opponents. Gary Russell Jr. worked his younger brother’s corner on the same night he’ll make a mandatory defense of his title against Mongolia’s Tugstsogt Nyambayar in a main event Showtime will televise.

Mexico’s Marrufo, 28, fell to 12-10-2 (1 KO). Marrufo is 2-5 in his past seven fights.

Earlier Saturday night, another Russell brother, Gary Antonio Russell, beat Jesus Martinez by disqualification.

The 27-year-old Russell (17-0, 12 KOs) was ahead 50-45 on all three scorecards when Gonzalez disqualified Colombia’s Martinez (27-11, 13 KOs) for repeatedly hitting Russell low and holding in the fifth and sixth rounds. Their eight-rounder was stopped at 1:31 of the sixth round.

Later Saturday night, veteran southpaw Jamontay Clark comfortably out-boxed Anthony Lenk to win their eight-round junior middleweight match by unanimous decision.

Cincinnati’s Clark (15-1-1, 7 KOs) defeated Lenk (16-7, 7 KOs), of Niagara Falls, New York, by scores of 79-73, 79-73 and 78-74. His victory enabled Clark to bounce back from an eight-round split draw to Sebastian Fundora (13-0-1, 9 KOs) in his last fight, August 31 in Minneapolis.

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