Novak Djokovic joins calls for Australian Open to address schedule issues

• Concerns raised over late finishes at Melbourne Park
• It's really gruelling,' says Serbian nine-times champion

Novak Djokovic has added his voice to calls for changes to be made to the Australian Open schedule amid growing concern over player welfare and fairness at this year's tournament at Melbourne Park.

Andy Murray was forced to back up just a day and a half after a gruelling near-six hour epic against Thanasi Kokkinakis that did not finish until 4am local time, a match that highlighted the issue for the first time at this year's grand slam.