Novak Djokovic will hope to take another step towards a record 25th Grand Slam title on Saturday when he plays in the Australian Open third round, with the Melbourne tournament braced for 40C temperatures.

The Serbian great faces 75th-ranked Dutchman Botic Van de Zandschulp for a place in the last 16, while reigning champions Jannik Sinner and Madison Keys are both in action.

The forecast scorching weather has forced a change of schedule, with matches moved forward to allow more play before the temperatures hit their predicted peak in the late afternoon. As the mercury rises, men's champion Sinner of Italy plays another American in 85th-ranked Eliot Spizzirri on Rod Laver.

Second seed Sinner is bidding to win the Melbourne major for a third time in a row, emulating Djokovic.

The 38-year-old former world number one Djokovic is third up on centre court.

Djokovic, who has been scaling back the number of matches he plays to wring the most out of his ageing body, said: "I'm really happy I'm able to play this way, considering the lack of competitive matches for more than two months.

"It's all been positive so far, positive signs." (AFP)