Collins returns to knock Osaka out of US Open
The tournament winner in 2018 and 2020, Osaka's exit followed reigning champion Emma Raducanu's departure hours earlier as Flushing Meadows bid a first-round farewell to its past two champions.
The last first-round match on the schedule was one of the most intriguing pitting two players who produce their best on hard courts. Collins was the losing finalist to Ash Barty at this year's Australian Open and Osaka is a two-time winner of the same tournament in addition to her US Open titles.
Both players also came to New York on the comeback trail after injury-interrupted campaigns.
Collins missed the entire North American hardcourt swing withdrawing from San Jose, Toronto and Cincinnati because of a neck injury while Osaka sat out the entire grasscourt season before falling in the opening round of the Toronto and Cincinnati events.
"I lost to Naomi three times before, so going into the match I had a lot of information on what I kind of needed to do better, areas I could improve," said Collins. "I felt happy just to be out here playing.
"I think when you face as many challenges as I've faced with some of the things I've been dealing with, you're kind of more grateful to kind of be out here."
Despite the layoffs Collins and Osaka delivered high-energy tennis which was welcomed by fans who stuck around for a match that got underway late Tuesday evening and finished early Wednesday morning.
Osaka had dominated their three previous head-to-head meetings with Collins unable to take even a single set from the Japanese former-world number one and in two of those contests she was chased off the court in less than an hour.
But the 19th seeded American came out determined, taking a tense opening set in a tie-break 7-5.
In the second set, Osaka would grab the early break and a 2-1 lead but Collins would immediately break back and then again at 5-3 and hold serve to clinch victory.
The American will next face Spanish qualifier Cristina Bucsa who was 6-4 6-4 winner over Slovenian Kaja Juvan.