EWARK, N.J. — The idea all along was for Zab Judah to wait patiently for the eighth round, conserving his energy for a late run at another world title.

It turns out he didn’t even need the eighth round.

The former undisputed welterweight champion knocked out Kaizer Mabuza early in the seventh Saturday night, regaining the IBF junior welterweight title he first held more than a decade ago.

Judah immediately ran to his corner and leaped onto the ropes at the Prudential Center as a large contingent of fans who made their way from his home borough of Brooklyn — including former heavyweight champion Mike Tyson — rose to their feet and cheered.

“I promised Jesus I would not mess around,” Judah said, “and I delivered on that promise.”

He also delivered on the promise he made to Pernell Whitaker, the Hall of Famer who joined his training camp prior to this fight. Whitaker was intent on teaching Judah some defense, and wanted him to stay behind his jab through the first two-thirds of the fight.

By then, according to their plan, Mabuza would be exhausted and Judah would be able to land that famous uppercut that carried him to the IBF belt for the first time in 2000 — and a closet full of other title trinkets after that.

“Mabuza was a tough guy. I don’t want to disrespect him at all,” Judah said. “I could have gotten wild a little sooner and really gotten after him, but I told Pernell I would go to the eighth with my jab, stay composed and use my jab to open up my offense.”

Judah (41-6, 28 KOs) sure found some offense, landing a devastating straight left early in the seventh round. Mabuza fell halfway through the ropes in the corner and referee Sam Viruet gave him a standing count before allowing the fight to continue.

It was a questionable move by Viruet because Mabuza was still plenty woozy. Judah pounced right away and landed several more blows that finally put the South African out on his feet.

“I feel very, very bad, but it obviously was not meant for me to be tonight,” Mabuza said. “I really think this is about my lack of fighting experienced fighters. I think Zab had the advantage because he’s fought many, many good fighters.”

And he’s earned the chance to fight several more.

It was an emphatic victory for the 33-year-old Judah, who was beginning to look his age in a debatable split decision victory over Lucas Matthysse last November. Many believed he had lost a step, and those fast hands that had touched the likes of Floyd Mayweather Jr. and Miguel Cotto during his dazzling professional career had finally slowed down.

Mabuza (23-7-3) must have been thinking the same thing early in the fight, wading right into Judah’s right jab without any trouble to deliver his own counterpunches.

Mabuza even startled Judah in the fourth round when he landed a glancing blow that knocked him off balance. Judah was forced to put his glove on the canvas to stabilize himself and the referee ruled it was a knockdown, sending Judah running across the ring in disbelief. After taking a moment to collect himself, Judah promptly came out and slapped Mabuza with another jab.

The South African appeared to win a close sixth round, too, before the fateful seventh.

“He’s bigger than me, but the Lord delivered me,” Judah said, unable to contain his smile. “He got me with the right people and brought me back.”

This was the third straight time Judah had fought at the Prudential Center, but he may have to take his title on the road for a bigger payday. Among the possible opponents waiting for him in a loaded 140-pound division is former champion Devon Alexander, who hails from St. Louis — the same city where Judah beat Cory Spinks to win his welterweight title years ago.

There are certainly others out there, including fellow titleholders Timothy Bradley and Amir Khan, but Judah will have to see how things shake out the next couple months.

While that’s happening, he’ll cherish being a world champion again.

“Look, he’s in the hottest division in boxing, and I think he just made a statement with that fight,” said his promoter, Kathy Duva. “He’s obviously dedicated himself in a way to changing his life, and I think he’s going to take all these young guys to school.”

Copyright 2011 by The Associated Press