Novak Djokovic returns the ball against Roberto Carballes Baena during the US Open first round. Photo: IC

Serbian tennis star Novak Djokovic came under fire in China after his comments on China's air quality went viral and irritated some internet users.

Djokovic admitted having experienced the "worst air quality" in China, sports news site Essentially Sports reported on Sunday. 

"China is probably the worst in terms of the quality of air," Djokovic said in a widely circulated clip of the post-match press conference at the ATP Cup 2020 on Saturday.

Some net users posted the Sunday report online and added another report from 2010 when Djokovic said the quality of air was so bad at the China Open in Beijing that players should have been equipped with oxygen tanks on the court.

The topic "Djokovic comments on China's air quality" became a hot trend with more than 2.8 million views on China's Twitter-like Sina Weibo as of press time. 

Although some admitted China's air quality problems, other expressed wrath for Djokovic's "unfriendly and exaggerated" remarks. 

"Why did he mention China and represent all of the players? How many places has he visited in China?" posted one user that received many likes.

Djokovic's official Chinese fan club released an announcement on Tuesday on Sina Weibo, saying that it was inappropriate for a public figure with a global influence to touch on the topic as it might lead to "over-interpretation" by media.  

Djokovic has not been to Beijing for four years and it was really inappropriate to say those words without new experiences, said the fan club. Also, he had not taken into account "the feelings of Chinese fans."

"I believe he did not mean to hurt Chinese supporters. If you make such comments, you have to be prepared to take the consequences," a Beijing-based sports commentator who requested anonymity told the Global Times on Tuesday.

"Sometimes a positive public image and friendship bond might collapse due to a very small case," he said.

Some fans defended the tennis star. 

"It's understandable that athletes are always more demanding about air quality than ordinary people," posted one user.

"Actually Beijing's air quality has improved significantly in the past few years. Let's hope he can come and visit again."

China has seen notable improvements in air quality in key regions, Liu Youbin, a spokesperson from the Ministry of Ecology and Environment (MEE) said in December. 

In the Beijing-Tianjin-Hebei and surrounding regions, the number of days with officially "good" air quality in November 2019 jumped 18.6 percentage points to 63 percent compared with the previous year, data from the ministry showed.

The Serbian is extremely popular in China for often expressing a favorable impression of China and Chinese fans. 

In the post-match press conference in 2018 following his victory in the fifth Shanghai Masters, Djokovic said he felt the fans were really behind him and he always liked to come back to Shanghai, which made him feel at home.