Britain's Laura Robson will face Spanish 30th seed Anabel Medina Garrigues in her US Open second-round clash at 1600 BST on Wednesday.
The teenager booked her spot in the second round when her Japanese opponent Ayumi Morita retired.
Robson, 17, led 7-6 (7-4) 1-0 after 61 minutes of play when Morita quit.
"I feel pretty confident because it's the first time that I've qualified for a Grand Slam, so that's really good," Robson said.
"Having played three matches already on these courts I know how they play and exactly how the balls play as well, so I'm sure that makes it a lot easier for me because the main draw players wouldn't have played a match on these courts."
Their match quickly became a battle beween the British teenager's big serve and groundstrokes and her Japanese opponent's tenacity around the court.
Morita, the world number 46, was far more consistent than Robson, who mixed thumping forehand winners with unforced errors down either flank, and there were six breaks of serve in a topsy-turvy first set.
Robson, who had come through qualifying to reach the main draw for the first time, eventually took it on a tie-break and broke Morita for a fourth time at the start of the second set.
The Japanese player asked for the trainer during that game and, after taking a medical time-out at the next changeover, she was unable to continue.
"I'm definitely happy to be in round two but it was disappointing that she had to retire," Robson told BBC Radio 5 live.
"I know Ayumi pretty well and I'm sure she's really, really disappointed, but again I'm happy to be in the second round."