Jiri Prochazka dethroned Glover Teixeira to claim the light-heavyweight title at UFC 275 in a fight the new champion described as "a true war".

The 29-year-old was trailing Teixeira on two of the judges' scorecards, with the other judge having it level, when he won with a rear-naked choke submission in the fifth round.

That brought an end to a gruelling bout in Singapore, with Prochazka coming through nearly five rounds of relentless punishment from his 42-year-old opponent.

"It's amazing and I'm glad. It was a true war. Glover is a true warrior, and I like that," Prochazka, UFC's first Czech champion, said in his post-fight interview.

"I never thought... that's why it's good to not be thinking, you are in the middle of the fight.

"Next time I will be better. I was ready to end the fight whenever today, whether in the first or fifth round, it doesn’t matter, and it doesn't matter which technique."

Teixeira became the oldest first-time champion in UFC history when defeating Jan Blachowicz last October and was 30 seconds away from retaining his title against Prochazka.

Despite turning 43 in four months' time, Teixeira has no intention of calling time on his career following Saturday's loss.

"I gave my all out there, no excuses," he said. "His body shots took my gas away, I was gassed out to be honest. But I'm going to keep going."

Valentina Shevchenko defeated Taila Santos by split decision in the women's flyweight fight, meanwhile, in what was her seventh successful title defence.

"I want to keep going, I want to keep improving," Shevchenko said. "I want to keep fighting no matter who – bantamweight, flyweight, I am here. Bring it on."