NEW YORK (REUTERS) - Nick Kyrgios could not shake off a shoulder pain or cope with his frustration as he slumped to a 6-3 1-6 6-4 6-1 defeat by fellow Australian John Millman in the US Open first round on Wednesday (Aug 30).

The 14th seed had treatment at the beginning of the third set after levelling at 1-1, but the mercurial Kyrgios gradually appeared to lose interest in the match.

The 22-year-old received a warning for allegedly cursing and broke his racket as he produced a string of unforced errors at Louis Armstrong Stadium.

After conceding defeat on the first match point, Kyrgios wished good luck to Millman, who next faces Tunisia's Malek Jaziri or Brazilian Thiago Monteiro.