Nick Kyrgios has lashed high profile tennis coach Roger Rasheed on Twitter, saying he has "zero idea", and has also criticized David Cup captain Lleyton Hewitt in a telling post to Instagram
Kyrgios, who was an Australian Open first-round casualty, took to Twitter to blast his critics.
Speaking on radio, Rasheed -- a former coach of Lleyton Hewitt -- and Australian rules football champion Gerard Healy said they felt Kyrgios, as well as Bernard Tomic and Thanasi Kokkinakis, needed to improve their footwork.
Kyrgios, who also crashed out in round one of the men's doubles on Wednesday, didn't take the advice well.
"You blokes all have zero idea. It's comical people like yourself have an opinion of us. You blokes are anything but athletes, so how about you concentrate on your own s***. Zero credibility," Kyrgios tweeted.
"Like please explain to me the similarities between [AFL football] and tennis. Shut your mouth."
The 23-year-old said that Rasheed, who has also coached top Frenchmen Gael Monfils and Jo-Wilfried Tsonga, "should be ashamed".
Earlier, Kyrgios posted a screenshot on Instagram of Hewitt doing television sideline commentary from Alex de Minaur's players' box.
Kyrgios posted a poll to his followers, asking whose match Hewitt was watching.
He provided two options: "Demon" and "No one else".
Kyrgios removed the post not long after it appeared during de Minaur's second-round match.
Following his opening round loss Kyrgios batted off questions about Tomic's Davis Cup criticism of Hewitt, saying he hadn't seen the comments.