Hosts Malaysia are in disarray before the Thomas Cup knockout stages even begin after suffering a bad-tempered group stage defeat to Japan in which one player got involved in a spat with a heckling fan.
The 3-2 loss - Malaysia's first to Japan in badminton's prestigious men's team tournament - leaves the hosts in the side of the draw where champions China loom large.
Fairuzizuan Tazari compounded a miserable Tuesday night for the badminton-mad Malaysians at the Putra Stadium when he retaliated in kind to heckling and a rude gesture from a fan.
"I apologise to the nation. The prime minister's wife was present among the spectators and I am sorry that this happened," national doubles team coach Rexy Mainaky said.
"The fans have the right to feel unhappy over our players' performances. Our players did not do well and I take responsibility for their performances.
"Fairuzizuan should have remained calm and should not have reacted even though what the fan said was unacceptable. He has to pay for this behaviour and we will deal with that later."
The defeat means Malaysia lose their third seeding and face a tough quarter-final tie against Denmark to keep their hopes of a sixth Thomas Cup triumph alive.
If they do get past the Danes, China are likely to be next up in the semi-finals after the champions remained on course for a fourth straight title with an easy 4-1 victory on Tuesday over the South Koreans, who they also meet in the last eight.
Germany, Indonesia and India are the other three teams in the quarter-finals.
In the women's Uber Cup, China thrashed Malaysia 5-0 in their final group game to keep their bid for a seventh successive title alive and retain the top seeding for the quarter-finals, where they will meet India.
Malaysia, Indonesia, Russia, South Korea, Denmark and Japan round out the last eight at the May 9-16 championships.