Team China's disappointing performances at the BWF Thomas and Uber Cup finals in Bangkok last week have prompted an apology from badminton's national governing body.

For the first time in 26 years, China missed out on gold in both tournaments. The women's squad failed to retain its title in a 3-2 defeat to South Korea on Saturday following a disheartening 3-0 quarterfinal thrashing for the men against Indonesia on Thursday. The latter result equaled China's worst-ever performance at the Thomas Cup.

Acknowledging the teams' below-par displays, Zhang Jun, president of the Chinese Badminton Association, said: "I want to apologize to all the Chinese fans. Sorry we disappointed you. We were so confident to at least win the Uber Cup, and there's no excuse for the defeat. From the singles to the doubles, we have many problems to solve.

"The overall performance of the men's team was disappointing. The young generation of Chinese men's players is developing, but they still trail the world's top players. We need to find better coaches for them."

Reigning Olympic singles champion Chen Yufei's grueling opening victory over An Se-young set the tone for an epic Uber Cup final, in which defending champion China was going for a 16th title.

After 91 minutes of enthralling action, Chen prevailed 17-21, 21-15,22-20.

"There was actually pretty big pressure on me as it's a team competition. It wasn't easy as I'm usually competing in individual competitions. My rival played great today-really solid and patient," said the 24-year-old Chen.

"If I don't remain calm on the court, I can easily make mistakes, and I wasn't quite as patient as my rival. Toward the end of the match, I just told myself to slow down and the chances would come.

"In terms of intensity, I'm pretty sure this match is among the top three of my career."

An emotional An, who overcame Japan's world No 1 Akane Yamaguchi a day earlier, feared she had cost her teammates glory.

"I tried my best, as much as I could... I was at 20 points but then I lost control," she said of her failure to capitalize on three match points.

China, though, failed to build on world No 3 Chen's victory, losing both doubles matches.

"It really was a pity that we failed to earn a point for our team at the final," said Chinese doubles player Jia Yifan, who along with Chen Qingchen lost to Lee So-hee and Shin Seung-chan.

"Our team won the first point in the toughest way possible thanks to Yufei's brilliance, and that really boosted our confidence," added Jia.

"We also played well at the beginning of our match, but our rivals adapted and they're really strong mentally. We didn't control our pace well."

Doubles veteran Huang Dongping concurred, saying: "We weren't up to speed today. We played too conservatively, and my partner and I didn't coordinate well."

Singles star He Bingjiao earned China's second point with a straight-sets victory over Kim Ga-eun to tie the final.

China's 15th-ranked Wang Zhiyi was expected to overcome 46th-ranked Sim Yu-jin in the decider. However, Sim sprang a major upset by winning 28-26, 18-21, 21-8 in a thrilling 88 minutes as South Korea claimed its first Uber Cup title in 12 years.

"I can't believe it," Sim told reporters. "I also made mistakes but I tried to reduce the number of errors."

The thrilling, seven-hour Uber Cup final was the most-discussed sports topic on Chinese social media on Saturday night, accounting for over 10 trending topics on Weibo and the hashtag "Chen Yufei "viewed over 140 million times in the space of just an hour.

Many fans paid tribute to the women's team's perseverance and battling spirit, but there was also concern that Team China's dominance of the sport appears to be on the wane against rapidly improving rivals.

"The Chinese women's team was lacking in many details on this occasion, especially during the doubles matches," commented Chinese men's doubles legend Cai Yun, who won gold at the 2012 London Olympics, on Saturday. "When we had the lead, we made too many unforced errors and let our advantage slip away too easily.

"Everyone understands there is pressure, but our rivals performed so well. And when we lost the lead, our players were not patient enough. Then more mistakes were made, gifting more chances to our opponents."

Cai heaped praise on the South Korean team, singling out Sim as a special talent.

"What impressed me the most is how fast our rivals have grown, such as Sim Yu-jin. Her wrist is so powerful and she's very fast," he said.

"Even the male players would struggle to replicate some of her skills. That's why in such critical matches, aggressive attacks are better than defense."

The women's failings, though, pale in comparison to the struggles of the men's team, which has never managed to fill the void left by the retirement of legend Lin Dan.

After two routine Thomas Cup group-stage victories over France and Algeria, the Chinese men lost 3-2 to Denmark on Thursday before crashing out of the competition with a humbling 3-0 loss to Indonesia-a repeat of last year's final result.

"My performance was really weak and I was too hesitant. When we were tied at 11-11, I was too nervous and missed many chances. I tried to make some adjustments, but it was too late," said Chinese singles player Zhao Junpeng.

It was a similar story for 22-year-old Li Shifeng, who described his own singles defeat as "unacceptable".

Team China owns 10 Thomas Cup titles in total, winning five in a row during its heyday from 2004 to 2012 with Lin spearheading the charge.

However, the last of those triumphs was in 2018, with the team's failure to find successors to singles ace Lin and doubles legend Cai seeing China slip down the international rankings.

Cai reckons more patience is needed with the squad's rebuild.

"The defeats are not what we wanted, but I believe such defeats will motivate our players to improve," he said. "I believe our players will try even harder in the future."