Kim Birrell was handed a tough assignment against Paris Olympics silver medallist Donna Vekic, who lived up to her 24th seeding to advance in straight sets.
One of a record six Australians to successfully qualify for the women's singles, Birrell battled hard but ultimately bowed out 6-4 6-4 in one hour, 33 minutes on Monday.
Olympic silver medalist Donna Vekic was too strong for Kim Birrell at Flushing Meadows. (AP PHOTO)
Despite the defeat, Birrell will leave Flushing Meadows with a cheque for $US100,000 ($A160,000) - the biggest prize in tennis history for a first-round loser at a major.
The Gold Coaster was among seven Australians scheduled for day-one action.
Fellow qualifiers Priscilla Hon and 18-year-old Maya Joint plus 2022 quarter-finalist Ajla Tomljanovic play later.
Hon has an exciting opportunity against world No.2 Aryna Sabalenka, the reigning back-to-back Australian Open champion in the feature women's night match on Louis Armstrong Stadium.
Joint will make her Open main-draw debut against German veteran Laura Siegemund.
Alexei Popyrin will lead the Australian men's charge against Soon-woo Kwon, Rinky Hijikata - who made an inspired run to the second week last year as a wildcard - plays Alejandro Davidovich Fokina and Adam Walton faces Alexandre Muller.
Another 13 Australians play on day two, including 10th seed Alex de Minaur opening his campaign against American Marcos Giron.Â
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