Novak Djokovic has backed Danielle Collins for her cheeky response to hostile fans at the Australian Open and said the sport could afford to take itself a little less seriously. Collins blew kisses at the booing crowd and thanked them for paying for her next five-star vacation after beating local Destanee Aiava in the second round on Thursday.

Novak Djokovic called Danielle Collins' feisty reaction to Australian Open hecklers "funny" and "smart" after himself getting riled up during his third-round win on Friday.

Novak Djokovic won in straight sets against the hecklers, too. Djokovic responded to an Australian Open fan who yelled an angry message to him after the Serbian rolled to a 6-1, 6-4, 6-4 victory over 26th-seed Tomáš Macháč.

Novak Djokovic now holds another Grand Slam record as he officially surpassed fellow tennis legend Roger Federer on Wednesday when he played the 430th major match in his career. After Djokovic's first-round match at the Australian Open on Monday, he tied Federer for the record.

Novak Djokovic reacted to surpassing Roger Federer's Grand Slam record during his second-round win in Australian Open.