The world former champion from Ukraine won by scorecards of 115-113, 116-112 and 117-111 for the three judges. But those tallies didn't tell the story of what was a close, thrilling fight.

Lomachenko was coming back to the sport after walking away from a major title unification earlier this year when he returned to his homeland once Russia invaded Ukraine to enlist in the Territorial Defence force.

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Ortiz was his first fight back after coming out of Ukraine and returning to training. The American, the younger man by eight years, was taller with an advantage in reach. He put those dimensions to use with dynamic energy in the first round.

Ortiz threw hard shots from long range and stayed busy enough to keep the Ukrainian southpaw at bay. As early as the first round dark bruising became apparent under Lomachenko's right eye.

In these early rounds, Lomachenko found it hard to establish his own rhythm. Ortiz threw him off with intensity and hard punching. The Ukrainian ramped up his own work rate in response. As the bout progressed, he began to blast hard straight shots to Ortiz's head, reeling off fast lead left crosses.

Ortiz's own footwork was sharp and agile. Concentrated attacks forced Lomachenko to back off.

The Ukrainian made sure he finished the final two rounds strongly. He surged onto the front foot, linking together combinations of punches and fighting furiously to the end.

"I'm happy, I'm happy to be back in the ring and make this great show," Lomachenko said afterwards.

"He is a tough fighter, he is a good fighter."

Lomachenko dug deep to get through the contest. "You know what motivated me - four belts," he declared.

The holder of the four belts Lomachenko wants, the undisputed lightweight champion Devin Haney was ringside.

He could not confirm a defence against Lomachenko, yet, but opened the door to negotiations. "Hopefully we can get it on," Haney said.

"I will be ready," Lomachenko promised.

On the undercard Cuba's Robeisy Ramirez, a two-time Olympic gold medallist like Lomachenko, continued his professional progression.

The featherweight forced a stoppage in the ninth round of his contest with Jose Matias Romero.

American heavyweight Richard Torrez, who won a silver medal at the Tokyo Olympics, won his fourth pro bout, overwhelming Ahmed Hefny quickly in three rounds.

Duke Ragan, another Olympic silver medallist, got past Luis Lebron, winning their eight rounder unanimously, 77-75, 78-74 and 79-73.

Nico Ali Walsh, the grandson of Muhammad Ali, won his undercard bout. He traded blows with Billy Wagner but landed enough power shots to make sure of a unanimous decision win, 59-55 and 58-56 twice.