Novak Djokovic, Coco Gauff roll to Australian Open's 4th round. Naomi Osaka retires due to injury and Jessica Pegula was upset in the third round.

Novak Djokovic has overcome some trouble breathing and played quite well for a straight-set victory over 26th-seeded Tomas Machac to reach the fourth round at the Australian Open.

Novak Djokovic has suggested tennis needs to embrace change, after suspecting the younger generation may be struggling to maintain their focus during long Grand Slam matches. Djokovic clashed with a spectator giving him abuse during his hugely impressive straight-sets third round win against Tomas Machac,

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.