Former Wimbledon champion Petra Kvitova was taken the distance by Japan's Misaki Doi before advancing to the second round of the US Open 6-2 3-6 6-1.
The seventh-seeded Czech hit 29 winners but the same number of unforced errors on a windy day in New York.
Kvitova, the 2011 champion at the All England Club, has never advanced past the fourth round at Flushing Meadows.
She eventually powered through against the tenacious 22-year-old Japanese left-hander, who is ranked 92nd in the world.
"In the first round of Grand Slams it's difficult all the time so you have to be focused," Kvitova said. "I didn't play my game all match. I didn't have focus. I have to have more confidence."
The 23-year-old will next face Serbian Bojana Jovanovski, who ousted Germany's Andrea Petkovic 6-2 6-4.
She was joined in the next round by another the 2008 French Open winner, Ana Ivanovic, who dispatched Georgia's Anna Tatishvili 6-2 6-0 in only 58 minutes.
The former world No 1 had enjoyed good preparation for the US Open until a first-round defeat by Alize Cornet in Cincinnati and faces American Varvara Lepchenko or Romanian Alexandra Dulgheru next.
After Wimbledon, where she fell in the secound round, Ivanovic parted with coach Nigel Sears and is now working with fellow Serbs Zlatko Novkovic and Branko Penic and the 25-year-old is happy with the progress she is making.
"I've been playing really well and I had a few tough losses," she said. "It's obviously hard, more so emotionally than anything else. I'm very confident with my game.
"I know I did a very good preparation. I have a new team with me. Obviously it takes time to get comfortable, to get things to work smoothly. I'm very happy at the way everything is."
Meanwhile, sixth seed Caroline Wozniacki continued her impressive recent form with a 6-2 7-5 win over China's Ying-Ying Duan.
Italian fourth seed Sara Errani, a semi-finalist in New York last year, recorded a rare 'double-bagel' against Olivia Rogowska from Australia 6-0 6-0, while her doubles partner Roberta Vinci, overcame some shaky serving before beating Timea Babos 6-4 6-2.
Babos converted all three of her break points, but Vinci broke the Hungarian's serve six times.
Russian 14th seed Maria Kirilenko beat 2009 US Open semi-finalist Yanina Wickmayer of Belgium 6-1 6-1 while her compatriot Elena Vesnina, the 22nd seed, crushed Annika Beck from Germany 6-1 6-1.
But Slovakian 17th seed Dominika Cibulkova fell at the first hurdle, losing 6-4 6-3 to Elina Svitolina from Ukraine while 20th-seeded Nadia Petrova went down 6-3 6-4 to Julia Glushko from Israel and 31st seed Klara Zakopalova lost 6-3 6-3 to Taiwan's Hsieh Su-Wei.
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