Venus Williams defeats Kateryna Kozlova despite 63 unforced errors

— -- NEW YORK -- Venus Williams needed three sets to win her 18th first-round match at the US Open.

She defeated Kateryna Kozlova of Ukraine 6-2, 5-7, 6-4 despite 63 unforced errors and improved to 18-0 in the Open's first round. Only Chris Evert (19-0) has a better record in the first round in the Open era, according to ESPN Stats & Information research.?

Williams led 5-2 in the third set, but the 22-year-old Kozlova pushed her to the limit in the 2-hour, 42-minute match.

Williams, a two-time winner in Flushing Meadows, next faces Julia Georges, who defeated Yanina Wickmayer 6-3, 6-2.

Also on the women's side,? Simona Halep gave herself "less than nine" for her quick work against Kirsten Flipkens.

The Romanian was ahead 6-0, 5-0 with countrywoman Nadia Comaneci cheering her on. Comaneci was the first gymnast to score a perfect 10 at the 1976 Montreal Olympics.

Halep, the fifth seed, was unable to complete the "double bagel," however, as she wound up winning 6-0, 6-2.

Halep said she wasn't perfect, but she was pleased with her play against the Belgian. She got 69 percent of her first serves in and won 12 of 15 points at the net.

Halep, who reached the semifinals of the US Open last year, will next face Lucie Safarova, a 6-4, 6-4 winner over Daria Gavrilova.

In other matches,? Ana Ivanovic?tumbled out of the US Open in the first round for the second straight year after a 7-6 (4), 6-1 loss to Denisa Allertova of the Czech Republic.

A former No. 1 player who has slipped to 31st in the rankings, Ivanovic was serving for the first set at 6-5 but struggled with her serve and faltered in the tiebreaker. The 2008 French Open champion finished with seven double-faults and 41 unforced errors.

At the Open, she has reached the fourth round or better five times, including a career-best quarterfinal run in 2012.

Meanwhile, 2011 US Open champion? Samantha Stosur?advanced with a 7-5, 6-7 (4), 6-1 win over Camila Giorgi, who had an ace to win the second-set tiebreaker.

Stosur, however, streaked out to a 4-0 lead in the deciding set and next will face Zhang Shuai, who defeated Ellen Perez 6-1, 6-1.

The Associated Press contributed to this report.