Keith Thurman retains welterweight title with unanimous decision over Shawn Porter

Keith Thurman can throw a heavy right hand, but what’s made him an unbeaten world champion is instinct.

So when he encountered a rabid Shawn Porter pursuing him heavily, pressing him to the ropes, throwing damaging punches to the body and head, Thurman reacted with calculation.

And by employing sufficient defense, positioning himself to land the defining punches of close rounds and throwing that right, Thurman remained World Boxing Assn. welterweight champion on Saturday at Brooklyn’s Barclays Center.

Judges Eric Marlinski, Waleska Roldan and Steve Weisfeld each scored the bout 115-113 in Thurman’s favor as he improved to 27-0.

Two of the judges awarded Thurman four of the last five rounds to help him keep the belt, and immediately trigger calls for a rematch from entertained fans in the arena and those watching on CBS’ first prime-time boxing card since Muhammad Ali-Leon Spinks I in 1978.

“I want to thank Shawn Porter for a tremendous fight, he’s a great warrior,” Thurman said. “Defense is the key to victory. He smothers his punches a lot and makes it difficult for the judges to score. I was able to rock him with clear, effective blows and I believe that was the difference today.”

In a bout hyped as the step forward from the Floyd Mayweather Jr. and Manny Pacquiao retirements, Thurman said he employed Ali’s famed rope-a-dope in the first half of the bout.

The superbly conditioned Porter (26-2-1) fought with all the fervor to be expected from a former champion who lost his International Boxing Federation belt in what was comparably a withdrawn 2014 effort against Kell Brook at StubHub Center.

Porter has entirely shed that style, chasing and pounding Thurman with hard punches to the head and body in the second round, letting his intentions known.

While a left by Thurman rocked Porter in the fourth, the challenger’s aggression and creative shuffling as he moved forward left Thurman searching for an effective response as two of the judges gave Porter four rounds between the second and seventh.

“We worked hard, Keith is a great champion,” Porter said. “I think I won the fight, but I’m satisfied because the competitor came out tonight.”

A cut emerged over Thurman’s left eye in the ninth round, but the champion landed a powerful left hook that wobbled Porter in the 10th, and after getting the nod in a close 11th, he again landed the clearer blows in the 12th, to hear ring announcer say, “And still … ” at the end.

“We need that rematch,” Porter said. “I know the fans want that rematch. If he gives me another chance, I’m going to work hard in the ring and leave with his title.”

Statistics that showed Porter connected on 236 of 662 punches to Thurman’s 235 of 539, while Thurman landed 203 power punches to Porter’s 177.

“To have a fight with that kind of anticipation — the best fighting the best — and get a fight of the year candidate from it, that’s boxing at it’s best,” promoter Lou DiBella said. “A draw would’ve been fair, but Keith would’ve kept his belt anyway. There’s got to be a rematch.”

In the substitute bout for the canceled Jesus Cuellar-Abner Mares featherweight title fight, Norwalk’s Oscar Molina suffered his first pro loss.

Molina was stopped by unbeaten junior-middleweight Jarrett Hurd of Maryland in the 10th round.

In the 10th, Hurd (18-0, 12 knockouts) outlanded Molina, 33-7, according to CompuBox, and he landed the final seven punches before referee Ricky Gonzalez halted at two minutes, two seconds the action that steadily turned one-sided.

Follow Lance Pugmire on Twitter @latimespugmire