SINGAPORE - At the second time of asking, Christian Lee became the youngest One Championship world champion on Friday (May 17).

In front of a sellout crowd of approximately 12,000 at the Singapore Indoor Stadium, the 20-year-old beat Shinya Aoki via a technical knockout 51 seconds into Round 2 to become One's lightweight world champion for the first time.

He showed great heart to slip out of an armbar in the first round before seeing off Aoki with a barrage of punches in the second of five scheduled rounds.

This was Lee's second shot at a world title after a split decision defeat by Australia's Martin Nguyen in their featherweight title fight last May.

Lee is a Canadian who has a Singaporean father and fights under the Singapore flag like his sister - women's atomweight world champion Angela Lee - even though the siblings are not citizens.

In the co-main event of the night, Regian Eersel overcame a slow start to beat fellow Dutchman Nieky Holzken by unanimous decision after going the full five rounds to win the lightweight kickboxing world championship.

The 26-year-old impressed with some fast and furious combinations, and flying knees, flooring Holzken with a hard right hand to the head with 30 seconds left in the fourth round.

Eersel said: "It was a great honour to fight such a great opponent, it was a really hard fight.

"But now, I'm here to protect this belt for as long as I can. Singapore, I will be back!"

Singapore's Amir Khan was knocked out by Turk Saygid Guseyn Arslanaliev's uppercut two minutes and 56 seconds into the first round of the lightweight world grand prix semi-final fight.

At least he lasted longer than the highly touted One Championship debutant Sage Northcutt, who had crossed over from the Ultimate Fighting Championship.

After being hit by a flurry of punches, the American karate expert was decked by Brazilian Cosmo Alexandre's ferocious right hook, as the referee stopped the welterweight bout just 29 seconds in.

Meanwhile, all of the night's featherweight kickboxing world grand prix quarter-finals went into the third and final round as Russian Dzhabar Askerov, Frenchman Samy Sana (both by unanimous decision), Thailand's Smokin' Jo Nattawut (technical knockout) and Petchmorakot Petchyindee Academy (split decision) progress to the final four and remain in the running for the US$1 million (S$1.38 million) grand prize.