BEIJING, June 24 (Xinhua) -- Three top Chinese table tennis players didn't show up for their second round singles matches at the ITTF China Open on Friday night and Chinese sports authorities vowed to probe into the matter.

Ma Long, Fan Zhendong and Xu Xin, the top three in the men's world rankings, made no appearances at Friday night's matches in the southwestern city of Chengdu while world number four Zhang Jike quit the competition on Thursday due to a waist injury.

Later on, a spokesperson of China's General Administration of Sports said the withdrawal was "was a breach of professional ethics and showed no respect to their rivals and the audience."

"We have urged the Chinese Table Tennis Association to investigate into the case and deal with it seriously," the spokesperson added.

Ahead of Friday's competition, the three players and coaches Qin Zhijian and Ma Lin posted identical messages on their social media accounts that they "don't feel like playing" because they missed their former coach Liu Guoliang.

On Tuesday, Grand Slam champion-turned coach Liu was named as its vice president by the Chinese Table Tennis Association (CTTA) and was no longer the "chief coach" of the Chinese table tennis team.

According to a reform plan unveiled on Tuesday, the CTTA abolished the positions of "chief coach" and "head coaches" in the Chinese team, and will instead set up two coaching teams for men's and women's players.

"These reforms will better prepare the Chinese team for the 2020 Olympic Games in Tokyo," a CTTA spokesperson said on Tuesday.

Liu, named head coach of the Chinese men's team in 2003, was promoted to chief coach in 2013 while also taking the helm of the men's team. He handed the men's team to Qin Zhijian in April 2017 while remaining as chief coach till Tuesday.