China thrashed India 5-0 in the Sudirman Cup on Sunday, but the defending champions were given a tough workout by their unfancied opponents while Taiwan managed a surprise win against Malaysia.
So distraught were the Chinese officials over their players' lacklustre performances in their opening Group A match that they snubbed the official press conference after their tie.
The eight-time winners of the trophy, who are gunning for their fifth consecutive crown, took more than three hours to subdue their opponents to virtual guarantee themselves a place in the quarter-finals.
The third team in Group A are former champions Indonesia, who play India on Monday.
With only three teams in each of the four groups, the top two countries will qualify for Thursday's quarter-finals.
More worryingly for China was the form of world champion Wang Yihan, who was stretched to three games by upcoming Indian star P. V. Sindhu. Sindhu was playing in place of the injured Saina Nehwal.
Saina, who has moved up to number two in the world rankings, withdrew from the tournament as she has a hairline fracture on her toe.
The lanky Wang Yihan, who spoke after her 19-21, 21-16, 21-14 victory, said: "She (Sindhu) is a tough opponent.
"I should have won the first game but threw it away. She is young and hungry and took me by surprise and I couldn't cope.
"I found my rhythm in the second game and took control from then on. I hope I can play in more matches after this."
In Group C tie, Taiwan stunned hosts Malaysia 3-2 tie to take a step closer to reaching the quarter-finals.
It was the beleaguered former world No. 1 pairing of Koo Kien Keat-Tan Boon Heong who let Malaysia down when they lost 21-18, 21-18 to Sheng Mu Lee-Chia Hsin Tsai.
The former All-England champions, who have not won a major title in over three years, may now be dropped when Malaysia face Germany in a must-win encounter on Tuesday.
"We thought we would be in control, but we were proven wrong. They (Sheng Mu -Chia Hsin) were clearly stronger front court, and their attacking was better," a disappointed Kien Keat said after the match.
When questioned if they should play against Germany next, Boon Heong said: "It depends on our coaches. As for me, my confidence has dropped a little after this defeat."
Malaysia's points came from world No. 1 Lee Chong Wei and mixed pair Chan Peng Soon-Goh Liu Ying.
In another Division 1 match, Denmark outplayed Singapore 4-1.
The Europeans, who are undergoing a transitional period following the retirement of legendary shuttlers Peter Gade and Tine Baun, will take on Japan on Tuesday.
Wang Yihan of China returns a shot against P. V. Sindhu of India at the 2013 Sudirman Cup world mixed team badminton championships in Kuala Lumpur on May 19, 2013. China thrashed India 5-0 in the Sudirman Cup, but the defending champions were given a tough workout by their unfancied opponents while Taiwan managed a surprise win against Malaysia.