Terence Crawford wins by TKO when Amir Khan can’t continue after low blow

An accidental low blow delivered by Terence Crawford brought a sudden ending to his welterweight title defense against Amir Khan on Saturday night at Madison Square Garden.

As Khan was writhing in pain from the sixth-round punch, his trainer, Virgil Hunter, reported that he no longer could fight, making Crawford the winner by technical knockout.

“The coach stopped the fight,” referee David Fields said.

Hunter explained afterward, “I didn’t want to send him back out there without his legs … he was in paralyzing type of pain.”

Crawford (35-0, 26 knockouts) knocked down Khan (33-5) in the first round on an overhand right to the top of the head. That harmed Khan’s strategy to try to rack up early rounds and eke out a decision. Instead, banged up, he absorbed more hurtful blows in the next four rounds as Crawford, ranked the No. 1 pound-for-pound fighter by The Times, delivered effective punches.

Khan was shaking his right hand in the third round as if he hurt that, too. Then, in the sixth, Crawford sent a forceful punch that clearly struck below the belt, and Khan bowed in agony.

“Khan could have recovered. He had five minutes to recover. He was looking for a way out,” Crawford promoter Bob Arum said. “He was looking for a place to fall. I don’t think Khan wanted to continue, and the next round or two would’ve ended the fight anyway.”

The crowd of 14,091 roared boos objecting to the disappointing ending, as those who paid $70 for the pay-per-view likely were, as well.

“I could tell I was breaking him down. It was just a matter of time,” Crawford said. “I just took my time. I was disappointed the corner stopped the fight in that manner, but Virgil is a great coach, and he was looking out for his fighter. I know he didn’t want to go out like that.”

Hunter said Khan didn’t object to his decision, elaborating, “If you get hit wrong in the testicles, five minutes is not enough.”

In victory, Crawford sought out fellow unbeaten welterweight champion Errol Spence Jr., the International Boxing Federation champion who fights for Arum’s rival Al Haymon’s Premier Boxing Champions.

“The fight I want next is Errol Spence,” Crawford said. “Whenever he is ready, he can come and get it.”

But Arum unleashed a blistering post-fight tirade at Haymon, accusing him of being committed to never allowing a Crawford-Spence bout. He went as far as urging fans not to support PBC bouts.

“Al Haymon won’t make fights … Spence won’t fight Crawford not because of Spence, but because of Al Haymon,” Arum said. “He’s running a scam of a company, and people have to realize he is ruining the sport of boxing.

“To not make a Spence fight with Crawford, which is a fight that all fight fans want, why? He only has his fighters fight in his own camp unless he gets fighters he knows his fighters can beat. That’s the scam.

“Spence believes he will beat Crawford. Al Haymon does not believe.”

In the co-main event, Teofimo Lopez remained in quite the hurry to become a world champion.

“I’m moving on to the main stage,” Lopez (13-0, 11 knockouts) said after knocking out his fifth foe in five bouts at the Garden by finishing Finland’s Edis Tatli 1 minute 32 seconds into the fifth round.

After Lopez watched the formidable Tatli stand up to early power blows that have allowed the Brooklyn phenom to overwhelm others on his quick rise, he began to batter Tatli (31-3) with hard punches in the fourth that reddened the Finn’s face.

Lopez maintained the pressure in the fifth and delivered a hard right to the gut that caused Tatli to crumble to his knees on the canvas, and he failed to stand by the count of 10.

The victory moves Lopez to that main event he wants in July, when he’s expected to challenge International Boxing Federation champion Richard Commey. He hopes that path will take him to an early 2020 showdown for all four lightweight belts against three-division champion Vasiliy Lomachenko.

“I want a world title shot next,” Lopez said. “We promised to take over the show, and once again, I took it over.

“As long as it’s for a title, I’m ready to go. No one can take my power.”

Lopez referred to needing to shore up some issues in his training regimen — likely nutrition — after he was seven pounds over the 135-pound lightweight limit the night before Friday’s weigh-in.

But his power, set up by his comfort in the pocket, is progressing and his insistence to prove his credentials against champions makes the personable Lopez perhaps boxing’s most intriguing young draw.

Earlier, Shakur Stevenson stepped up in class impressively by overwhelming recent 130-pound title challenger Christopher Diaz by unanimous-decision scores of 100-90, 99-91, 98-92 in a featherweight bout.

Stevenson, a 2016 U.S. Olympic silver medalist who occasionally spars with his close friend Crawford, showed the benefits of that work by complementing his gifted hand speed by fighting inside at times with Diaz, neutralizing the veteran who thought – along with trainer Freddie Roach – that his strength and experience would decide the outcome.

Instead, Stevenson (11-0) peppered Diaz (24-2) with rapid combinations to the head and body, and when Diaz landed something effective and tried to corner his younger foe, Stevenson either wisely held or casually slipped away.

Stevenson rattled Diaz’s head with a combination in the fifth, then buckled his knees with a left to the head in the sixth before cruising through the later rounds.

“He’s a great fighter, but I came in there to outbox him, and that’s exactly what I did,” Stevenson said.

Stevenson called himself “the smartest boxer in boxing,” and named WBO featherweight champion Oscar Valdez as a potential foe. Valdez has a June 8 title defense.

Former elite prospect Felix Verdejo scored a convincing unanimous-decision victory over Bryan Vasquez on scores of 97-93, 97-93, 98-92.

Verdejo (25-1) exerted early power to keep Vasquez in a defensive posture in the early going, and although the lingering effects of a 2016 motorcycle accident have left him susceptible to facial scarring — a cut opened under his left eye in the fourth round — he flashed good head movement and worked the body of Vasquez (37-4) to pile up rounds.

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While matchmakers assessed Verdejo needs to work on building up his durability, he backed up Vasquez in the seventh with a power punch to the head, showed an impressive jab and jarred him again in the eighth.

“I worked hard for this fight. The jab and body punches were key,” Verdejo said. “I’m going to keep working harder to get even better.”

The undercard included some promising young fighters, including unbeaten super-welterweight Carlos Adames (17-0, 14 KOs).

Adames, a left-hander from the Dominican Republic, began to weaken Brooklyn’s Frank Galarza (20-3-2) with body shots in the third round, then dropped him with a left to the head early in the fourth.

With the tough Galarza seeking to exchange, Adames delivered a series of punches that stopped him from answering and brought referee Benjy Esteves to stop the bout 1:07 into the fourth.

“This was a message to all of the 154-pounders. I want to face all the best, and I’m determined to fight for a world title by the end of the year,” said Adames, trained in Riverside by Robert Garcia. “I felt great with [Garcia]. … He told me to pressure [Galarza] because he was ready to go.”

Brooklyn middleweight prospect Edgar Berlanga left a quick, solid impression in his debut as a Top Rank fighter by scoring a first-round technical knockout of Samir Barbosa (37-16-3).

Berlanga (10-0, 10 KOs) battered Barbosa from the start, then landed a flush punch to the nose that sent the Brazilian backing to the ropes with both arms spread wide, convincing the referee to stop the fight 46 seconds into the opening round. Berlanga returns May 25 in Kissimmee, Fla.

lance.pugmire@latimes.com

Twitter: @latimespugmire