Australia's 14th-seeded Nick Kyrgios crashed out in the first round of the US Open on Wednesday with a right shoulder injury then beat himself up verbally for lacking dedication.

Two weeks after upsetting Rafael Nadal on the way to the biggest final of his career, Kyrgios lost to 235th-ranked compatriot John Millman 6-3, 1-6, 6-4, 6-1.

Kyrgios, who had been the highest-seeded obstacle in Roger Federer's path to the quarter-finals, grabbed his right shoulder in the fourth game of the third set.

"Early in the third set I hit one serve and I never felt the same after that," Kyrgios said. "Something didn't feel right in my arm."

Still uncertain of the problem, Kyrgios lamented a year that saw him make second-round exits at the Australian and French Opens and retire from his Wimbledon opener with a hip injury that nagged him for weeks.

"I've had a diabolical year at the Slams," Kyrgios said. "It doesn't surprise me. It's just the story of my career, really. I will have good weeks. I'll have bad weeks. It's just a roller-coaster.

"I'm not having the greatest year like I should have done, but the last three months has been a nightmare, really."

Uncertain about his status for Australia's Davis Cup semi-final in just over two weeks, Kyrgios downed himself for his lack of dedication, saying his French coach, Sebastien Grosjean, deserved to work with a more inspired player.

"I'm not good enough for him," Kyrgios said. "He's very dedicated. He's an unbelievable coach. He probably deserves a player that's probably more dedicated to the game than I am.

"He deserves a better athlete than me. I'm not dedicated to the game at all. He has helped me a lot, especially in training sessions.

"There are players out there that are more dedicated, that want to get better, that strive to get better every day, the one-percenters. I'm not that guy."

Asked if he might be one day, Kyrgios said, "I really don't know. Probably not, honestly not."

The 22-year-old beat Nadal on the way to his first ATP Masters final at Cincinnati, where he fell to Grigor Dimitrov.

"In Cincinnati, I was not doing anything different. I was probably less dedicated than I was this week," Kyrgios said, citing pre-match basketball games and daily milk shake runs to an ice cream shop.

"I was less dedicated. And this week I was dedicated and my shoulder starts hurting."

Asked how worried he was about injury issues and needing a break, Kyrgios said, "I don't know. I don't know. I keep letting people down. So I don't know. I really don't know."

- 'Arm is totally dead' -

Kyrgios told a physiotherapist his troubles during an injury timeout and while getting treatment during changeovers.

"One serve and arm is totally dead. It's so dead and numb. It's incredibly weak," said Kyrgios. "How can something happen all of a sudden? I wasn't feeling it at all and then Bang, one serve. I lost power in my serve."

Frustration grew as Kyrgios screamed an obscenity while glaring at his right hand after slamming down a racquet following the fifth game of the third set, earning a language warning.

"My forehand is painful. It's so annoying," Kyrgios told the trainer. "I try hard and then one serve I can feel it. I don't get it. I don't know what to do.

"I'm feeling good. I finally have a good week last week, come to the US Open feeling good, playing a good match against an Aussie, third set and it's throbbing."

After his last available treatment, Kyrgios lost eight of the last nine games to drop the match.

Source: AFP