Second seed Simona Halep survived a scare at the US Open by overtaking American wild card Danielle Collins 6-7 (2) 6-1 6-2 in Monday's opening centre court match.
The French Open finalist moves on to face Slovakian Jana Cepelova, a 2-6 7-5 6-1 winner over Spain's Maria-Teresa Torro-Flor, in the second round of the season's last grand slam.
But the 22-year-old Romanian had a tricky time getting by Collins, a US college champion from the University of Virginia.
Down a break at 3-4, the 20-year-old American brought the set back on serve at 4-all and with her confidence growing the collegian ran away with the decider by taking advantage of a slew of errors from Halep.
That shock seemed to snap the Romanian back to attention, and bring her groundstrokes under control as she roared to victory over Collins, who was playing her first tour-level main draw match.
"She played a tough match, I want to congratulate her," world number two Halep said in an on-court interview. "First set I was a little bit nervous. This court is huge.
"It's my best ranking ever and best moment of my life. I have to enjoy it, but it's not easy. Everybody is telling me I have chances to win this title."
Halep, who broke through last season by notching her first six career tour titles, has two titles this season and finished runner-up to Maria Sharapova at Roland Garros in her first grand slam final.
Britain's Johanna Konta fell at the first hurdle with defeat by Israel's Shahar Peer.
Konta secured a place at Flushing Meadows on her own ranking for the first time, but was unable to take advantage, losing 6-2 6-3.
At 118 in the world, Konta is ranked 37 places higher than Peer, but the Israeli has the pedigree, having once been the world number 11.
And Konta found Peer simply too steady, a tally of 15 winners and 34 unforced errors for the British number two rather telling its own story.
A fascinating match-up between 19th seed Venus Williams and Kimiko Date-Krumm of Japan, the oldest players in the women's draw, was joined by some pesky bees that refused to leave them alone.
First the 43-year-old Japanese player and later 34-year-old Williams dipped, ducked and danced away before ballgirls helped usher the determined bees off the baseline.
When finally left to play tennis on sun-bathed Arthur Ashe Stadium court, seven-time grand slam singles winner Williams stung Date-Krumm 2-6 6-3 6-3 to advance.
Asked about who presented the peskier test in the two-hour match, two-time US winner Williams said: "The bee was a challenge but easily the answer is Kimiko.
"The way she hits the ball is like no one else on tour and it's never easy to get a rhythm with her, and all our matches have been tough. So I'm happy to have pulled it out."
Agnieszka Radwanska also progressed, beating Sharon Fichman in straight sets.