"I don't know. I don't know," Zappavigna, holding back tears, told AAP when asked if he might quit the sport after a 38-fight career.

It was not the physical toll on his face and body that hurt, it was that Zappavigna - after losing his first world-title fight in 2011 in Las Vegas - had come so close to getting his second chance at a prized belt.

It will be former kickboxing champion Lipinets who will fight Namibia's recently-crowned IBF champion Julius Indongo next year for the world title.

The boxer known as Lenny Z was the early aggressor on Saturday and led on two of the judges' scorecards in the first four rounds, but in the fifth Lipinets, who looked hurt several times and had a large gash over his right eye, struck the Australian with a straight left.

Zappavigna hit the canvas, but got back up.

Despite the knockdown, Zappavigna and Lipinets were even on two of the judges' scorecards heading into the fateful eighth round, with the third judge leaning toward the Kazakh 67-65.

Lipinets ended the fight when he connected with two more lefts.

Zappavigna's knees buckled, he fell to the centre of the canvas and was unable to get back on his feet.

"My eyes were cut, I couldn't see in one round because I had so much blood in my eyes," said Zappavigna, who was comforted in the locker room by his wife Paris and young son Leonardo Jr.

After training in Los Angeles the past two years with the great Freddie Roach, who was in his corner at the Galen Centre, Zappavigna flies back to Australia on Tuesday.

He will make a decision on his career in the coming weeks.

Zappavigna's professional record drops to 35 wins (25 knockouts) and three losses while Lipinets improves to 11 wins.