Pumped-up defending champion Novak Djokovic admitted he was “pushed to the limit” by dangerous American Frances Tiafoe on Wednesday, who took the World No. 1 to four gruelling sets at the Australian Open. 

The Serbian top seed looked in control after taking the first set, but lightning-quick Tiafoe, who reached the quarter-finals two years ago, refused to go quietly. He bounced back to take a close second set before Djokovic dug deep to emerge a 6-3, 6-7 (3/7), 7-6 (7/2), 6-3 winner and continue his relentless march towards a ninth Australian Open title.