Badminton and controversy are not exactly strangers, but a row involving the air conditioning at the world men's singles final has caused a headache the sport could do without.
The southern China showdown between home favourite Lin Dan, the four-time champion, and Malaysia's Lee Chong Wei, his main rival and the world number one, had the makings of a classic.
But Lin's win was overshadowed by the apparent failure of the air conditioning mid-match, fuelling conspiracy theories and possibly contributing to Lee's withdrawal on a stretcher with cramp as he faced match point.
"It was so hot inside and Chong Wei was dehydrated. This led to him suffering cramps," Lee's coach Tey Seu Bock told Malaysian newspaper The Star.
"This is not right. The players were suffering. At one point, Chong Wei was struggling to breathe," he added.
An AFP reporter said the air-conditioning at Guangzhou's Tianhe Gymnasium, which had been plaguing players at one end of the court, went off at the start of the second game, when Lin moved to the draft-affected side.
As temperatures rose and sweltering spectators fanned themselves furiously, Lin -- who was trailing after the first game -- found his range with a series of pinpoint shots in the airless arena.
"Changes in conditions during a match have a huge impact on the outcome," one badminton expert, who did not want to be named, told AFP.
"Throughout the tournament there had been strong drift on the far side of the court, where the wind was blowing from behind and from the side due to the air-conditioning. It tended to make players' returns more likely to go long or wide when they played at that end, and they had been adjusting to that all week."
The air conditioning stayed off for the rest of the match and came back on again after it had finished, the AFP reporter said.
The Badminton World Federation (BWF) investigated the incident. But in a statement on Thursday, the world body said Chinese officials had insisted the air-conditioning was not turned off, but was simply set too low.
"The local organising committee has confirmed to the BWF that the air conditioner in the venue was not turned off at any time during the finals, but that the air conditioner was set on low from the beginning of the day," the statement said.
"However, due to the increase in the number of spectators attending on finals day -- and in particular during the men's singles match -- the temperature went up and the venue became hotter."
Despite China's denial, the incident provided more ammunition for the cynics, who raised their eyebrows when Lin, whose ranking had dropped to 100 after an extended break following the Olympics, was handed the tournament's only wild card by the BWF because of his "fan appeal".
Lin then landed in the opposite side of the draw from Lee, meaning he could not meet him before the final. He breezed into the final without dropping a game, even against China's world number two Chen Long in the quarter-finals.
Lin's fifth world title meant that China's superstar, the two-time Olympic champion, had completed a fairytale run on home turf against the unfortunate Lee, despite playing only three competitive matches all year.
Raphael Sachetat, chief editor of the Badzine website, said the behaviour of the cooling system may not have affected the outcome of the final.
"However, if it is proven that the organisers have shut down the air-conditioning on purpose to give an advantage to Lin Dan, then it is clearly something that needs to be looked into as it definitely goes against the values of the sport and fairness," he told AFP.
"Lin Dan deserves better than that -- he has proven he could win without any outside help. The sport deserves better than that as well, especially after the Olympic controversy and the two banned players from Thailand more recently."
The BWF's new president Poul-Erik Hoyer has taken over a sport still battling the fallout from last year's Olympic scandal, when eight women's doubles players were disqualified for trying to lose group games to gain an easier quarter-final draw.
And in recent weeks, badminton's image suffered again when two Thai players were handed long bans for brawling during a men's doubles final in Canada.
Addressing media before Sunday's finals, Hoyer pledged to come down hard on match-fixing in the wake of the Olympic row.
"It shouldn't happen and I don't want to see it happen, but I cannot guarantee you that it wouldn't happen because it's been going on in many sports," he warned, adding: "It is important that we can act, and will act if anything happens."
Badminton has a history of intrigue. A Badzine survey found that in 2011, 20 percent of all-Chinese matches went uncompleted due to walkovers and retirements. The figure dropped to less than one percent when Chinese players were facing competitors from other countries.