He dramatically abandoned the game after losing his first set with Johnson on a tie-breaker.
Following Kyrgios' latest controversy, the the 22-year-old blamed his retirement from the contest on a stomach bug. He was given a penalty for an audible obscenity during the tiebreaker, which he had also threatened to quit if he lost. "He can go in a spiral and get in the doldrums and then it takes quite a lot to lift him", said Croft. "He then needs other people around him and the right advice that he can respond to and lift his spirits a little bit".
What do you think about Kyrgios' punishment for what happened at Shanghai?
"Guys, I want to apologise to the fans in Shanghai and those that watched around the world on TV today", he posted on Twitter after the match.
The tweet was later deleted.
The ATP has however docked Kyrgos his first-round prizemoney of $27,000 for failing to undergo a medical after the match and fined him $US10,000 for unsportsmanlike conduct.
He has subsequently also withdrawn from the doubles tournament in Shanghai.
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It's the second year in a row the hot-headed Aussie has been punished for bad behavior at the Shanghai Rolex Masters.
Kyrgios was banned for eight tournament weeks and fined a total of $41,500 after he appeared to tank at the same tournament a year ago.
But that's not all. Big deal. I don't owe them anything.
"What's happening here?" he asked, before muttering: "Exactly why I shouldn't come here".
"Obviously didn't have a great one previous year, obviously got suspended after that".
It appeared that Kyrgios had walked off in protest at the officiating but the Australian released a statement on social media insisting that he "was just not strong enough to continue because I've not eaten much the past 24 hours".
The incident comes just two days after the temperamental Kyrgios lost to Rafael Nadal in the final of the China Open after becoming frustrated by a line call in the first set.