The 28th-seeded Australian blasted Hoang 6-4, 6-2, 6-4 to match his deepest US Open run and booked a date with 43rd-ranked Andrey Rublev, who beat Roger Federer at Cincinnati two weeks ago, to decide a berth in the last 16.

"He's a young, fearless player who has been playing really well the last couple weeks," Kyrgios said. "He plays big from both sides. He's a great player."

Kyrgios won their only meeting last year in Moscow, recalling, "It was an incredibly tough match."

The 24-year-old Canberra-born product had two minor issues in his match, the first over a collar inscription "Just Do You" that officials feared violated clothing rules, forcing Kyrgios to fold down his collar.

"I think they thought it was a slogan, but it wasn't," Kyrgios said. "It wasn't anything to do with a marketing thing. I think they must have read it wrong. I think they thought it said 'Just Do It' like the slogan.

"It was a mix-up. It's all cleared up now. I can wear that. I can wear the collar up."

The second dispute came late in the third set when Kyrgios thought he won a point, heard umpire Nico Helwerth call the game and score, only to have it overturned on what he considered a video challenge made far too late.

"He called game, then my opponent challenged once the umpire called game," Kyrgios said. "I just thought that wasn't right."

After arguing to no avail, Kyrgios smacked a service winner to settle the matter and seize a 5-3 lead, then made an exaggerated squat and jump motion to look at the chair and his rival, then give the umpire one more look after walking away, just to make sure the game was truly over.

Kyrgios, who won titles this year in Acapulco and Washington, has an open draw quarter after three top-10 players lost in the first round.

Kyrgios called the ATP "corrupt" on Tuesday, unhappy about his record $113,000 fine for actions at Cincinnati where he profanely insulted an umpire, but pulled back on the remark Wednesday, saying he is unhappy at what he sees as a double standard on ATP enforcements and punishments.

"I expect consistency and fairness with this across the board. To date that's not happened," Kyrgios tweeted.

The ATP has started an investigation into the comment as a major policy violation, but Kyrgios said the tour has not reached out to him about the matter and he doesn't expect them to do so.