Men's world number one Viktor Axelsen had his aura of invincibility shaken Friday at the season-ending badminton World Tour Finals in Bangkok with a surprise loss to India's H.S. Prannoy.

The defeat was only the third this year for the dominant 28-year-old Dane, who eventually succumbed 14-21, 21-17, 21-18.

But Axelsen -- who won gold at the Tokyo Olympics last year -- still advances to Saturday's semi-finals albeit with his confidence slightly bruised.

The Badminton World Federation shifted its $1.5 million flagship event to the Thai capital's Nimibutr Arena after original host China dropped the tournament due to its tough Covid restrictions.

Prannoy had nothing to lose in Friday's clash after two losses earlier in the week meant he was ineligible to advance to the next round.

Axelsen started strong, winning the first game 21-14, and looked like he was cruising towards a straight-games victory as he took a four-point lead early in the second.

But the 30-year-old Prannoy, ranked 12th in the world, did not give up and after the interval clawed his way back to claim the second game 21-17.

Prannoy -- who helped India make history in May when they hoisted the Thomas Cup for the first time -- then deployed clever net work to build an advantage in the final game, putting Axelsen under pressure and leading to a 21-18 win.

In the other men's group, Indonesian hotshot Anthony Ginting booked himself and compatriot Jonatan Christie semi-finals berths after notching up a hat trick of victories.

Christie's advance to the next stage was dependent on Ginting beating Singaporean Loh Kean Yew.

Seventh-ranked Ginting upstaged world number three Loh 21-12, 23-21.

"I'm really, really feeling happy and grateful," Ginting told reporters after the match, joking that Christie owed him one.

Japan's Kodai Naraoka rounded out the men's semi-finals line-up after knocking over China's Lu Guang Zu 21-19, 21-15.

In the women's draw, badminton world number one singles star Akane Yamaguchi saw off a threat from Indonesian newcomer Gregoria Mariska Tunjung to book a spot in the semis 21-15, 13-21, 21-18.

He Bing Jiao from China clocked her third win of the tournament, overpowering local hope Busanan Ongbamrungphan from Thailand 8-21, 22-20, 21-13 to advance.

And Olympic champion Chen Yufei knocked out Korean young gun An Se Young in straight games 21-16, 21-12.

Play is still underway in Bangkok to round out the semi-final draw.

Taiwan's Tai Tzu Ying and Thailand's Ratchanok Intanon will battle it out later Friday for the last spot in the next stage of the tournament.