Undefeated junior middleweight prospect Marques Valle took a major step up against Damian Sosa in his first scheduled 10-rounder Wednesday night, and although Valle handled the two extra rounds just fine, he couldn’t quite cope with his experienced, relentless Mexican opponent.

At the end of 10 tremendously entertaining, hard-fought rounds at the ProBox TV Events Center in Plant City, Florida, underdog Sosa captured a deserved split decision by scores of 96-94, 97-93 – and a hard-to-figure 98-92 in Valle’s favor.

Valle, 25, from nearby Tampa, had the crowd on his side and flashed his talent from the mid-range in the opening round. But it wasn’t long before the slickness, experience and punching accuracy of Sosa, 27, let him know just how tough he had been matched. Back and forth they went in what seemed a dead-even fight through the first six rounds, with “El Samurai” Sosa getting the better of the exchanges in close – especially when he backed Valle to the ropes – while Valle did his best work with a little space separating him from his motivated veteran foe.

Valle lost his mouthpiece four times in the fight, but that was a mere footnote – it was Sosa’s pressure and two-fisted attack that proved the headline. Valle’s corner told him, as his right eye swelled, that he was losing after eight rounds, and entering the 10th, they told him to “lay everything on the line right now.” Valle responded, seeming to hurt Sosa a bit with body shots in the final rounds and snapping his head back at one point with a heavy right hand. But it wasn’t quite enough.

After having fought just one eight-rounder, Valle saw his record slip to 10-1 (7 KOs) following his first 10-rounder. With the victory, +240 betting underdog Sosa improved to 25-2 (12 KOs). But both fighters did themselves proud in a scrap that led ProBox TV broadcaster Chris Algieri to describe the venue they were in as “the house of action.”

To open the broadcast, former title challenger Ronny Rios got back in the win column in his first fight in 22 months, stopping familiar ProBox TV face Nicolas Polanco with a left hook to the body in the fifth round of a scheduled featherweight 10-rounder.

Rios, 34, was in charge with his body attack and pressuring style from the start, showing no obvious rust as he upped his record to 34-4 (17 KOs).

The taller Polanco (21-6-1, 12 KOs) came out jabbing and moving, but Rios calmly closed the distance and fired to the flanks with both fists. Both men received warnings from referee Frank Santore Jr. in the second round, and the action picked up in the third, with first the Dominican Polanco landing a long right uppercut and then California’s Rios shaking him just a bit with a chopping right.

As the rounds wore on, it became increasingly apparent that Polanco, 31, had neither the firepower nor the slickness to dissuade Rios. The +550 underdog Polanco started the fifth round aggressively, perhaps sensing it was go-big-or-go-home time – and “go home” was the result. A perfectly placed left to the side crumpled Polanco to the canvas, where the best he could do was transfer at the count of nine from his knees and elbows to just his knees.

The end came at 54 seconds of the round – and it was about two more minutes before Polanco was finally able to get to his feet.

Eric Raskin is a veteran boxing journalist with more 25 years of experience covering the sport for such outlets as BoxingScene, ESPN, Grantland, Playboy, Ringside Seat and The Ring (where he served as managing editor for seven years). He also co-hosted The HBO Boxing Podcast, Showtime Boxing with Raskin & Mulvaney and Ring Theory, and currently co-hosts The Interim Champion Boxing Podcast with Raskin & Mulvaney. He has won three first-place writing awards from the BWAA for his work with The Ring, Grantland and HBO. Outside boxing, he is the senior editor of CasinoReports and the author of 2014’s The Moneymaker Effect. He can be reached on X or LinkedIn, or via email at RaskinBoxing@yahoo.com.