"Every person that’s bought a ticket to come out here and heckle me ... it’s all going towards the Danielle Collins fund."

Tennis purists felt unsettled as Danielle Collins went right at a rowdy Australian crowd after taking out a hometown favourite in incredible scenes. But the exchange is actually healthy for the sport.

MELBOURNE, Australia — Count Novak Djokovic as being in Danielle Collins' corner. He thinks her response to booing fans at the Australian Open was absolutely fine — which should come as no surprise, given the way Djokovic gets into back-and-forths with hecklers at his matches, including Friday night at Rod Laver Arena.