Defending champion Jan O. Jorgensen of Denmark sailed to the Indonesia Open finals after Germany's Marc Zwiebler was forced to retire due to illness on Saturday.

Third-seeded Jorgensen faced a tough fight from Zwiebler, who refused to let up and kept points tight up to 17-17 in the first set.

The German, however, made unforced errors afterwards that handed victory to Jorgensen.

Embracing the victory, last year's men's singles winner Jorgensen said: "It feels amazing to be in two finals in a row. That's crazy."

Zwiebler said he was forced to retire after what appeared to be food poisoning.

"I ate food at the hotel and something was not right. I spent the night and day in the bathroom. Before the match, I got a high temperature. I went to see a doctor. It was 39 Celsius," Zwiebler said after the game.

"Normally I should have not played but I wanted to give it a try," he added.

The Dane said he expected a hard-won battle when he faced Japanese rising star Kento Momota at the finals on Sunday.

Momota defeated Indian ace shuttler Parupalli Kashyap, whom a day earlier toppled badminton world number one Chen Long of China.

Kashyap had played well, attacking the eight-year younger Momota with his precise smashes while maintaining his composure at the same time.

But in the end, it was the Japanese who sealed the game after a gruelling one hour and 17 minute battle that resulted in a score of 12-21 21-17 21-19.

"Today's match is quite exhausting... Maybe it was pure luck. I saw the opponent having a trouble in the third set, so I took to the netting game," Momota said.

Defeated Kashyap lamented the result.

"Just can't finish it very well... I can't take the last two points. Very upset, very disappointed," he said.

It was a good day for the Japanese.

In the women's singles, Yui Hashimoto of Japan won over Wang Yihan of China with 21-17 9-21 21-17.

She will face Thailand's Ratchanok Intanon in the women's singles final.

It was bad news for host Indonesia, which had to witness its favourite mixed doubles, as well men's doubles team bow out after losing to China's shuttlers team.

Its remaining hope lies with Nitya Krishinda Maheswari and Greysia Polii to win a title in women's doubles on Sunday.