The seventh-seeded Czech weathered another tough U.S. Open match in the first round Tuesday, needing three sets and nearly two hours to beat 92nd-ranked Misaki Doi.
Kvitova won 6-2, 3-6, 6-1 on a windy day at Arthur Ashe Stadium.
"I like big matches on the big stadium, but the people it's too much crowds for myself, I think," she said.
Roger Federer's U.S. Open got off to a late start but a routine one.
The 17-time major champion beat Grega Zemlja in straight sets Tuesday in a first-round match postponed from the night before because of rain. Federer is seeded seventh at Flushing Meadows, his worst since 2002. But he looked like the guy used to being seeded first in the 6-3, 6-2, 7-5 win.
Federer had 12 aces and 35 winners.
The 62nd-ranked Zemlja, from Slovenia, reached the third round at Wimbledon this year. That's one round further than Federer, who was stunned by 116th-ranked Sergiy Stakhovsky in his second match there.
Federer won 20 of 21 points at the net to advance in 93 minutes.
Kvitova has reached at least the semifinals at the other three major events; she has never made it past the fourth round at Flushing Meadows.
She's also struggled in the North American swing leading up to the U.S. Open, but she made a breakthrough last year. Kvitova won two of those tournaments and reached the semifinals at another in 2012, then matched her longest run at the year's last Grand Slam tournament.
"So I have good motivation to improve my results here," she said.
The final set Tuesday was closer than the score in this rare matchup of two lefties. After Kvitova went up a break at 2-0, Doi had a chance to break right back but couldn't convert.
Two years ago, Kvitova became the first reigning Wimbledon women's champion to lose her first U.S. Open match in the same season. She was in danger of another early exit Tuesday when she made 15 unforced errors in the second set.
But she's hardly fazed by three-set matches. Kvitova recently played six straight across three tournaments, winning four of them.
Doi, from Japan, fell to 0-4 against top 10 opponents.
Later on Ashe, 17-time major champion Roger Federer will play his first-round match originally scheduled for Monday night. His opener against 62nd-ranked Grega Zemlja of Slovenia was postponed by rain.
Others in action Tuesday included top-seeded Novak Djokovic and two-time Australian Open champion Victoria Azarenka.
No. 10-seeded Roberta Vinci, a quarterfinalist at Flushing Meadows last year, beat Timea Babos 6-4, 6-2. She's reached a career-high ranking this summer at age 30 after making the round of 16 at the French Open and Wimbledon.
No. 13-seeded Ana Ivanovic and 14th-seeded Maria Kirilenko got off to quick starts, each winning in under an hour. Ivanovic, the 2008 French Open champ, beat Anna Tatishvili 6-2, 6-0. Kirilenko won 6-1, 6-1 against Yanina Wickmayer, a semifinalist at Flushing Meadows four years ago whose ranking has fallen to 57th.
Christina McHale, a 21-year-old from Englewood Cliffs, N.J., snapped a five-match losing streak by beating 45th-ranked Julia Goerges 6-4, 6-3. McHale's ranking had fallen to 114th.
On the men's side, Milos Raonic won his first Grand Slam match while seeded in the top 10. The 22-year-old Canadian defeated qualifier Thomas Fabbiano of Italy 6-3, 7-6 (6), 6-3.