Ironically, the worst behaved current tennis player is Australian, Nick Kyrgios.
Ironically, Kyrgios is smart enough to NEVER get 3 official warnings and lose a game.
He certainly never moans and complains about his warnings afterwards, or threatens lines people, or brings out the race card, or the sexism card. He can certainly never be warned for coaching, as he does not have one.
BTW - Serena is way worse behaved than Kyrgios and has been over a long period of time.