Another day, another Nick Kyrgios controversy. This time, the world No. 14 tanked his second-round match in the Shanghai Rolex Masters against world No. 110 Mischa Zverev, 6-3, 6-1. The flop comes just three days off the biggest title win of his career in the Rakuten Japan Open (and the Australian won his first round in Shanghai over Sam Querrey with some drama, 6-4, 6-4).

The boo-filled match against Zverev devolved into a comedy routine as Kyrgios delayed proceedings to argue with a fan who had shouted "respect the game" and "respect the people" after it became clear that he was not going to put in any effort.

Zverev jokingly said some of the serves felt like they were coming from his girlfriend, but still defended Kyrgios.

"You reach a point where you're mentally tired and some people react one way, some people react a different way,'' Zverev said. ''It doesn't say anything about whether he's professional or not.''

Kyrgios, when asked about the soft serving, said his arm was "a little sore."

Right after dropping his own serve, Kyrgios didn't try to return Zverev's, jumping away from the ball to give an easy hold.

Umpire Ali Nili warned Kyrgios that he "can't play like that. It's just not professional. [It's] a professional tournament." Kyrgios responded with, "Can you call time so I can finish this match and go home?"

Yikes.

Kyrgios was apologetic on Twitter afterwards, but will it be enough to reconcile with fans?

This isn't the first time that Kyrgios has tanked a match. He pulled the same type of stunt against Richard Gasquet in the fourth round of last year's Wimbledon, though not for the whole match.

Still a work in progress, indeed. Zverev will face Marcel Granollers in the third round in Shanghai.