Nick Kyrgios questions ATP Tour's treatment of Novak Djokovic again

Nick Kyrgios has again questioned the ATP Tour's consistency after Novak Djokovic apparently escaped with a fine after hitting a spectator with a tennis ball.

"I would've been defaulted and suspended until 2025," suggested a tongue-in-cheek Kyrgios on Twitter.

Djokovic's temper got the better of him twice in his 6-3 5-7 6-4 victory over Andy Murray on Saturday night to retain the Qatar Open title, causing umpire Carlos Bernardes to hand him two warnings, including the loss of a point on the second warning.

The first came in the sixth game of the first set when world No.2 Djokovic, annoyed after losing a point, slapped a ball into the crowd on the bounce, hitting a woman.

He was later warned again and docked a point after smashing his racquet in frustration during the second set.

It was the first incident that drew comment from Kyrgios, who recently completed a three-week suspension for "tanking" - not giving full effort - in a match at the Shanghai Masters, where he was also fined heavily.

It's not the first time Kyrgios has questioned the tour's treatment of Djokovic.

In May at the French Open Kyrgios got a warning from umpire Carlos Ramos for yelling "towel" at a ball boy and later referenced Djokovic going unpunished despite pushing away a match umpire when challenging a call in Rome earlier that month.

The Australian accused Ramos of "unbelievable bias" and said the code violation call was "f---ing bulls---" during his exchanges on the court.

Post-match he said there would be "a circus" if he pushed an umpire in the manner that Djokovic had.

Djokovic said hitting the spectator with the ball on Saturday night was an accident but admitted he may have got off lightly.

"I definitely didn't want to hit the ball at anybody," Djokovic said. "Just happened. Fortunate not to get a bigger fine. I have to be more careful I guess. I accept that I made a mistake."