Seething tennis fans who paid up to $450 per ticket for the night session on Tuesday have demanded answers after they were locked out of Rod Laver Arena for almost two hours.

The puzzling decision not to start day matches at the Australian Open until 1pm backfired in spectacular fashion, with the last on court tussle between Italian young gun Jannik Sinner and fifth seed Andrey Rublev not finishing until 1.21am.

An earlier quarter-final involving Novak Djokovic and Taylor Fritz went the distance over four tight sets, ensuring plenty of fans left the venue feeling weary as the sun began to set.

Injured Aussie star Nick Kyrgios was then dragged into the controversy, with his post-match interview with Djokovic making supporters endure a further delay.

In embarrassing scenes, those who paid premium prices for the night matches were left waiting outside as frustrations grew.

Inexplicably, Margaret Court Arena did not have a night session scheduled for Tuesday.

Tennis reporter Ben Rothenberg spoke for many when he labelled the scheduling of matches at Melbourne Park 'utterly unserious' on X.

Fritz said post match following his defeat against Djokovic that plenty of players have been bemused at the late finishes on court.

'It just screws up your whole clock,' Fritz said. 'I get it, matches go long some days. 

'But yeah, there's got to be something they [tournament organisers] can do to where people aren't playing until 2am/3am.

'I don't think people really fully understand how much time we actually have to spend doing stuff after we finish playing.....ice baths, treatment with physios, massages, all this stuff.

'If you finish at 2am, there is no chance I'm going to sleep until 5 or 6am.'

Last year, Aussie Thanasi Kokkinakis and veteran Andy Murray were on court for almost six hours, finishing their epic second round match just after 4am.

Incredibly, Lleyton Hewitt's third-round showdown with Marcos Baghdatis at Australian Open in 2008 finished at 4.34am, with the five-set thriller the latest completed match in Grand Slam history.

This year, the Australian Open started the tournament a day earlier in a bid to avoid unreasonable finish times.

'We have listened to feedback from the players and fans and are excited to deliver a solution to minimise late finishes while continuing to provide a fair and equitable schedule on the stadium courts,' Australian Open director Craig Tiley said in October.

On Wednesday, play was scheduled to begin on Rod Laver Arena from 12pm.