LAS VEGAS – Relentlessness is sometimes underrated. Saturday night it got its due.

In boxing, there is often more value placed on fast hands, flashy footwork and crushing power. This is all understandable because it is difficult to measure the power of relentlessness but on a night when he had more of it than one could have ever imagined, Antonio Margarito willed his way to the WBA welterweight title by simply refusing to acknowledge all the gifts Miguel Cotto possessed and simply countering them all by attacking him round after round until he collapsed.

“Pressure, pressure, pressure,’’ Margarito said after stopping Cotto at 2:05 of the 11th round. By then the champion’s eye had been slit open, his mouth and nose were bleeding and his spirit had been broken so completely that he twice took a knee before referee Kenny Bayless finally stopped what had morphed from a classic fight into a one-sided assault.

For 11 rounds at the MGM Grand Garden Arena, Margarito stalked the WBA welterweight champion, taking all Cotto threw at him and matching it with his relentlessly surging forward motion. It took a while but eventually that pressure broke Cotto down in the same way he had done to so many others fighters on other nights that had belonged to him.

This became clear by midway in a fight that was close on the scorecards even when the bout was stopped (two judges had Margarito leading 96-94 and a third had the fight even) but not if one looked at Cotto’s face.

There was written a story of pain and disillusionment, a sad tale of a beating so dominate by its end that there was nothing for a proud champion to do but fall to one knee without being hit and then leave for a lengthy stay at a local hospital.

“Miguel will not be here,’’ promoter Bob Arum said at the post-fight press conference. “The commission has asked him to go to the hospital immediately because of the number of stitches he’ll need and for observation because of the two knockdowns.’’

As Arum spoke, the new champion stood behind him wearing dark glasses to hide the damage he had suffered but his pain was nothing compared to what he had inflicted.

“I knew he was a better boxer but I am the heavier puncher,’’ Margarito (37-5, 27 KO) said after the stoppage.  “That was the game plan. Come out aggressive early, pressure him and knock him out. I got him with body shots and then I hit him in the head, got him with the uppercut and knocked him out.’’

Four inches taller and with a six-inch reach advantage, Margarito was too big, too strong and on this night at least too good for Cotto, who was a brave man trapped in what became a hopeless dilemma. The champion’s hand speed advantage was evident from the outset but even when he landed crisply he never once was able to shatter the iron-willed discipline of the challenger in front of him.

Unable to back him up or dissuade him for even a moment from continuing a well planned assault, Cotto suddenly found himself facing a problem to which he had no answer.

When a man keeps coming forward no matter what you hit him with, it becomes a distinct problem not easily solved. Saturday night, Miguel Cotto never was able to.

“I trusted my preparation,’’ Margarito said. “Cotto is obviously a strong fighter but slowly the tornado rumbled. I told the knockout would come and the knockout came.

“Once the sixth round came it was my time to press the action. He was getting weaker and I was getting stronger.’’

Although Cotto was scoring cleanly early, Margarito simply kept walking him down, stalking him like a man who had for too many years been denied this kind of big fight and someone was going to pay for it. That someone was Miguel Cotto, although it took a while for the full price to be paid for all those past slights.

After having been denied big-money opportunities by boxing’s biggest names, Oscar De La Hoya and Floyd Mayweather, Jr., Margarito finally had been given his chance by Cotto, who ducks no one. By the end, he also was ducking no punches in the final few rounds, a problem imposed upon him by his challenger.

“This was Margarito’s night,’’ Cotto (32-1) said before leaving for the hospital to have his badly dented and damaged face examined. “He’s an excellent fighter. He did his job better than I did.’’

As early as the second round Cotto’s nose was bleeding and Margarito kept boring in on him, pressuring him wherever he went. It mattered not how many counter punches he was hit by. He was here to do damage and no one, least of all Miguel Cotto, could dissuade him from it.

The challenger’s relentlessness and iron chin were already on exhibit as he kept wading through Cotto’s flurries and stinging jab, scoring as he did. The champion was trying to use Margarito’s relentlessness against him as best he could but with each passing round he was more and more feeling the sting of the bigger man’s punching power.

No matter what Cotto landed Margarito looked at him with the dead eyes of an assassin and then stepped toward him again. Cotto slipped and moved successfully for a while but as the rounds wore on he began to wear down until there was nothing left of him but a broken shadow.

This was a war of doggedness for a while but midway through the seventh round Margarito hurt Cotto for the first time, bloodying his nose and mouth again and driving him back to the ropes as the crowd roared for more.

Margarito was now all over the champion, battering his face in his own corner as blood again dripped from Cotto’s eye, nose and mouth. The damage Margarito was now doing was obvious and debilitating, although it would take four more rounds before Cotto would finally give in to it.

Cotto was far more defensive thereafter however, constantly trying to circle away but finding no safe haven except between rounds in his corner. The challenger was doing to him what  Cotto had so often done to his own beaten down opponents. He was suffocating him.

Late in round 10, with Cotto bleeding again from the eye and nose, Margarito nailed him with a left hook that sent him tottering sideways but a two-punch combination behind it was only a glancing blow. Had they landed flush, Cotto’s night might have been over but as things turned out he no longer had much longer to work or much more to give.

A minute into the 11th round Cotto’s face suddenly seemed a mass of red, bloodied and swollen after another flurry from Margarito. Completely spent, Cotto seemed to sense the end of his title reign was upon him and so was Margarito, who was landing a string of punches that began with the left uppercut that was always the greatest danger to Cotto.

A flurry behind that uppercut sent him down to one knee semi-voluntarily for the first time. When he got up he was already an ex-champion, although there was a bit more formality that had to be undertaken.

Margarito wasted little time getting to it. Cotto began to retreat with his arms spread wide, almost like a man saying, “Come on now. Enough already.’’

Margarito ignored him as he had all night, again walking straight at him with mayhem on his mind. He went to throw another combination but before he could land another punch Cotto took a knee again, conceding what had now become obvious.

When he got up again, Bayless looked at him but didn’t seem to know quite what to do next. Fortunately for Miguel Cotto, his uncle, who also serves as his trainer, did.

He leapt onto the ring apron and signaled his nephew had done enough. He had landed crisp punches that would have discouraged a less determined challenger. He had moved and slipped a lot of what Antonio threw at him.

He had done all he could but he had not done enough. Not on this night, one that belonged to relentlessness and to a guy who had been ignored and avoided in the past but could not be Saturday night.