Coco Gauff says scheduling matches during Australian Open night sessions remains a grey area after tournament organisers were criticised following day one at Melbourne Park.

The Australian Open began a day earlier than in previous years in the hope this would relieve pressure on match scheduling and avoid players taking to the court late at night.

This occurred last year when Andy Murray and Thanasi Kokkinakis did not begin their second-round match until after 10pm EDT, before finishing after 4am EDT.

But in the opening night session of this year's tournament on Sunday, defending champion Aryna Sabalenka and her opponent Ella Seidel did not take to the court on Rod Laver Arena until almost midnight.

The late start was unavoidable after Novak Djokovic was stretched beyond four hours in his win over Dino Prizmic in the earlier men's match, which started just after 7pm EDT.

The scheduling attracted criticism on social media but thankfully for Sabalenka, she only needed 53 minutes to wrap up a 6-0, 6-1 win over qualifier Seidel, with the match finishing just after 12:30am EDT.

Gauff, who won her first-round match on Monday afternoon, admitted tournament organisers were put in a difficult position when scheduling night sessions.

"It's like a tough thing because yes, at night it is probably our prime time and we can optimise (TV) viewers, but also we have to protect the players' health," she said.

"It's like a fine line."