Japan's defending champion Shoma Uno said he "gave everything" to overcome an injury scare and take the lead after the men's short programme at the world figure skating championships on Thursday.

Uno, competing in front of his home fans in Saitama, north of Tokyo, put himself in pole position to claim a second straight world crown with a season-best score of 104.63.

That put him ahead of 18-year-old American "QuadGod" Ilia Malinin on 100.38 and South Korea's Cha Jun-hwan on 99.64.

Uno was left sweating on the defence of his title when he fell and injured his right ankle in practice on the eve of the competition.

He said he had recovered in time to compete and "had to work a little harder than normal" to get the job done.

"I really gave everything I had," said the 25-year-old, who pumped his fist after completing his routine and came off the ice wearing a huge grin.

"I hadn't been in good form going into the competition so I wanted to work those emotions off when it began."

Uno said he thought he was in real trouble when he hurt his ankle on Wednesday but felt no pain when he took to the ice for his short programme.

But he cautioned that he was not out of the woods yet, after entering the competition with "doubts" over his ability to win.

"To be honest, before the short programme I didn't have the luxury of thinking about winning another title," he said.

"Now I'd like to put a little of that pressure on myself for the free skate."

- Miura, Kihara claim gold -

Self-proclaimed "QuadGod" Malinin lived up to his own hype with a spellbinding performance to claim a new personal best score in second place.

He arrived in Japan with a big reputation, having become the first skater ever to land the ultra-difficult quadruple axel jump in competition in September last year.

He did not include the move in his short programme but he dazzled from start to finish, dressed head to toe in black.

"I have no words to describe how I'm feeling right now -- I'm just shocked," a beaming Malinin told reporters, after receiving a standing ovation from the Japanese crowd.

"I've worked so hard these past couple of weeks, finding every small mistake and always working to improve it.

"I'm just very glad that I'm here and I delivered," he added.

Earlier in the day, Riku Miura and Ryuichi Kihara said they wanted to inspire a new generation after becoming Japan's first ever figure skating pairs world champions.

The Japanese duo survived a late slip to hold off Americans Alexa Knierim and Brandon Frazier for the gold.

The win gave Miura and Kihara an incredible season sweep, the pair having already claimed the NHK Trophy, Skate Canada, Grand Prix final and Four Continents titles.

Kihara said he hoped their latest win would usher in a new era of Japanese pairs success.

"I would love it if boys and girls watching this thought that they wanted to try pairs skating themselves and we get more and more Japanese pairs," he said.

"I hope people will look back in 10 or 20 years' time and say this was the catalyst for it changing."

Miura and Kihara took gold with an overall score of 222.16, ahead of Knierim and Frazier in second place on 217.48.

Sara Conti and Niccolo Macii won bronze to claim Italy's first ever world pairs medal on 208.08.

Russian skaters have again been banned from the competition because of the war in Ukraine.