By Jake Donovan

Cesar Barrionuevo stormed to the next stage of the World Boxing Council (WBC) welterweight tournament after tearing through Azael Cosio in five lopsided rounds Saturday evening in Guererro, Mexico.

Five knockdowns came of the night, which ended with Cosio flat on his back and ruled unfit to continue at 2:55 of round five. 

Barrionuevo had never previously fought outside of his native Argentina, nor had his level of competition suggested he was ready to move within a couple of wins towards a first career title shot. The southpaw - who turns 27 in February - had Cosio in trouble in the opening round, never looking back following the first time he's floored an opponent. 

The violent end came in the closing seconds of round five, Cosio (20-3-1, 17KOs) positioned as if to prepare to move towards his corner. Barrioneuvo made a point to punch through his target, landing a savage left hook to put Cosio down and out.

Barrionuevo improves to 30-3-2, 20KOs), also moving up the welterweight ladder. He will next face Sammy Vasquez, who advanced to to the next round of the WBC tournament with a 6th round stoppage of Aron Martinez. Their bout took place one week ago in Los Angeles, on the same Premier Boxing Champions (PBC) on Fox card that saw Danny Garcia claim the vacant WBC title with a 12-round win over Robert Guerrero.

Negotiations for Barrionuevo-Vasquez are due to begin immediately. The winner of that fight will either go on to face "wild card" selection Ray Robinson or go straight to the WBC title. Garcia is due to next face Amir Khan, whom he rallied to stop in four rounds in their July '12 super lightweight title fight.

Barrionuevo-Cosio aired live on TyC Sports in the United States and Argentina, as well as serving as part of a Televisa in Mexico.

Also appearing exclusively on the Televisa feed, Nery Saguilan and Miguel Roman kept alive their respective win streaks and title hopes, although by vastly different means.

Saguilan extended his win streak to 10 straight, although barely getting to that point after a split decision nod over Philippines' Leonardo Doronio in their 12-round lightweight bout. The visiting challenger won 114-113 on one card, while the other two judges offered that very same score in favor of Saguilan (37-5-1, 13KOs), who was deducted a point in round eight and forced to fend off a fierce rally from Doronio to prevail.

Roman had a much easier night in the office, picking up what was classified as a 4th round stoppage of Yogli Herrera. The 10-round lightweight bout was all one way, as Roman (54-11, 41KO) dished out a savage beating for three rounds. Herrera used the entire one-minute rest period to mull over whether or not to continue, opting out as the bell sounded to begin round four. 

Jake Donovan is the managing editor of BoxingScene.com. Twitter: @JakeNDaBox