Nick Kyrgios was a lightning rod for controversy at the U.S. Open this week but the fiery Australian was subdued after a third-round loss on Saturday and walked away quietly from the year's final Grand Slam.

Kyrgios did deliver a one-word jab at a line judge early in his straight-sets loss to Russian Andrey Rublev but otherwise steered clear of any of the sort of drama that he made headlines for earlier in the week.

The Australian delivered a serving masterclass against Rublev but generally lacked his usual intensity and at one point during the match a microphone picked up Kyrgios saying he did not even want to be there.

Still, after the 7-6(5) 7-6(5) 6-3 loss under the bright Arthur Ashe Stadium lights, the Australian 28th seed did not point the blame at anyone but himself.

"He played great tonight. Was super aggressive. I never felt comfortable. That was just credit to him playing his game. Yeah, it was tough," said Kyrgios. "Nowhere near my best tennis."

During the first set of his third-round loss Kyrgios did shout "whistleblower" from his seat in the direction of a line judge who had gone to the chair umpire to report foul language.

It marked a very subdued ending to a week in which Kyrgios got in hot water for calling the ATP corrupt, yelled at fans for leaving their seats during his serve, and threatened not to start a match over a dispute about his outfit.

When asked about the comment picked up by microphones Kyrgios said he has been on the road for over five months and he does not have much down time before playing for Team World at the Sept. 20-22 Laver Cup in Switzerland.

"We'll see how the scheduling works out. I guess that's a disadvantage playing from Australia," said Kyrgios. "I got the very important Asia swing. Don't want to miss that."

After Kyrgios suggested he may need rest, one journalist asked if he would in fact welcome a suspension for the way he spoke about the governing body of men's tennis.

"I don't know if I look at it like that," Kyrgios said smiling. "I don't know. I have no say in it. I guess it's out of my control."

Kyrgios was in no mood for controversy on this night, and even resisted getting into it with a reporter who asked what he needs to focus on to maximize his tennis potential.

"I don't know," Kyrgios shot back. "You guys are the experts. You tell me."