After missing the entire North American hardcourt season, American Danielle Collins showed no signs of rust battling past twice US Open champions Naomi Osaka 7-6(5) 6-3 on Tuesday and into the second round at Flushing Meadows.
The exit of Osaka, the tournament winner in 2018 and 2020, 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 arrived in 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.
"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."
Osaka, who lost to Amanda Anisimova in the first round of the French Open, sat out the entire grasscourt season before falling in the opening round of the Toronto and Cincinnati events.
The 24-year-old said she was happy to have played through the match without her back flaring up and only began serving on Sunday.
"Honestly, I just wanted to play without my back being in pain because it's kind of been bad for the entire hard court season since Toronto," Osaka told reporters. "I didn't serve until two days ago so I was really happy with how it went.
"Overall I wouldn't say that I played well ... I felt like I was on my back foot a lot," she added. "Everyone deals with injuries. For me, it's been more prominent this year, but it's something that I can learn (from).
"I learned a lot more about my body, I learned what's weak, what I can do to prevent it. I would say the sport is definitely very physical, but it's kind of my job to stay on top of it."
Despite the layoffs, Collins and Osaka delivered high-energy tennis that was welcomed by fans who stuck around for a match that got underway late on Tuesday evening and finished early on 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 28-year old American will next face Spanish qualifier Cristina Bucsa who was 6-4 6-4 winner over Slovenian Kaja Juvan.