9:24 AM ET

The title defense of Alexander Volkanovski is official.

The Korean Zombie, Volkanovski and Chan Sung Jung, both weighed in on Friday at 144.5 pounds. The main event of UFC 273 will feature a fight between Volkanovski and Jung.

Volkanovski is ranked fourth in the world pound-for-pound. Volkanovski and Jung are the top ranked at their weight class.

Volkanovski has won 20 fights in a row, including his first 10 in the UFC. At UFC 266 last September, the Australia native won a unanimous decision over Brian Ortega. Volkanovski won the UFC belt at UFC 245 in December.

Jung beat Dan Ige in a unanimous decision last June. The Korea native has won three fights in a row. The longest period of time between title fights in UFC history was between Jung and Jose Aldo, who fought for the title in 2013).

The UFC bantamweight title will be unified by champion Aljamain Sterling and interim champ PetrYan. The two weighed in at 134 and 134.5 pounds.

At UFC 259 in March 2021,Yan landed an illegal knee on him, which resulted in him being disqualification from the UFC bantamweight title. He has won six in a row.

While weighing in, he got very emotional, bending over before stepping on the scale and rubbing his eyes. He had neck surgery.

A lot of people wrote me off and thought my career was over, but I came back after that surgery and they didn't think I would ever play again.

The 6-ranked pound-for-pound fighter isYan. The 29-year-old Russian has won 11 of his past 12 fights. The interim title was won byYan by a unanimous decision.

Gilbert Burns, a former title challenger, will face off against one of the best prospects in UFC history, Khamzat Chimaev, at UFC 273. The men weighed in at 170 pounds.

Kay Hansen was 2.5 pounds over the 116-pound non-title limit. Hansen forfeited 20% of her purse to Piera Rodriguez for the bout.