Novak Djokovic showed great physical and mental strength to overcome injury and an in-form Taylor Fritz over five sets at the Australian Open on Friday night.

Following his three-hour, 25-minute triumph against the American, the World No. 1 discussed the unfortunate moment that caused his injury and what happened during his off-court medical timeout.

“[In the] beginning of the third set, I made this quick move on the return going to the forehand, rotating there, and I just felt a tear, I felt something happen,” said Djokovic. “[I] went out for a medical timeout where I was tested [and] evaluated. I have huge pain. I took the highest dose of anti-inflammatories possible.”

When Djokovic returned to the court, he was unable to stop Fritz from taking the next two sets as he struggled with his game, particularly on the forehand side. In a one-set shootout for a place in the fourth round, Djokovic took consistent risks on his second serve and claimed two breaks to reach the Australian Open Round of 16 for the 14th time.

“I honestly don’t know how I won this match,” said Djokovic. “I’m very proud. At the same time, [I am] sad and worried, because it’s definitely something serious happening with my injury. I don’t have much time to recover for the next match.”

Djokovic is due to meet Milos Raonic on Sunday for a place in the quarter-finals. The 17-time Grand Slam champion is taking all precautions to give himself the best possible chance of being ready to contest his 12th ATP Head2Head encounter against the Canadian (Djokovic leads 11-0).

“[I am] definitely not training tomorrow,” said Djokovic. “I’m coming here to evaluate further with [the] doctor and medical team, and do some ultrasound. [I will then] understand what’s really going on, so that the doctor and medical team can prescribe [the] best possible treatment, and the only [way] that I could even have the slightest chance to go out in less than 48 hours.”