Badminton world number one Viktor Axelsen survived a serious scare from H.S. Prannoy of India on Friday to advance to the semifinals of the Japan Open.

The reigning world champion and Tokyo Olympics gold medallist dropped the first game to the Malaysian Masters winner before finishing their nail-biting contest 19-21, 21-18, 21-8.

The Danish star struggled to find his usual form with an aggressive Prannoy applying pressure throughout the match.

"It was a tough match today. It could have gone both ways, I think," Axelsen told reporters after the game.

"But you know I am really happy about how I managed to pull through. It was physically really tough. However, I managed to win the crucial points in the second game and got a really good start in the third game. So all in all, really good."

Axelson will face fast-rising home star Kodai Naraoka, who beat China's Shi Yu Qi 11-21, 21-19, 21-14.

Naraoka, speaking before Axelsen secured his victory, said he will go to the next game with a challenger's spirit.

"I will have to make sure that I will be in the condition in which I can give my 100 percent," whichever player rises to the semifinals, he said.

Women's number two An Se-young of South Korea beat her childhood idol Ratchanok Intanon of Thailand 21-19, 21-10.

She will face Taiwan's fourth-seed Tai Tzu Ying, whom An beat last week in the final of the Korea Open.

"I have been able to perform well so far (this season) and show good results," An said after her victory.

"(Tai) is a good, skilled player. I will focus on my own performance," An said of her next match.

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