Novak Djokovic defied fierce heat and a battling performance from Taylor Fritz on Tuesday to reach the Australian Open semi-finals and stay on track for a record-breaking 25th Grand Slam title. The Serbian world number one struggled with the conditions early in the contest but came through 7-6 (7/3), 4-6, 6-2, 6-3 and will play Jannik Sinner or Andrey Rublev for a place in Sunday's final. "It was extremely hot when the sun was still out there," Djokovic said after the match at Rod Laver Arena, which stretched to three hours and 45 minutes. "Physically and emotionally very draining. Huge round of applause to Fritz for a great performance today and this tournament. "