Angelique Kerber nearly had a birthday to forget Wednesday.
The top seed in the Australian Open, Kerber needed three sets to fight off a challenge from German compatriot Carina Witthoeft, emerging with a 6-2, 6-7 (3), 6-2 victory in the second round at Melbourne, Australia.
"Actually, I'm always playing on my birthday," Kerber said. "I'm getting older, but, yeah, I think I will have a great day."
Kerber, who turned 29, held off Witthoeft on the same court where she won her first Grand Slam title last year. Kerber went on to capture the 2016 U.S. Open and reach the finals at the Olympics and the WTA Tour Finals.
Witthoeft, 21, was attempting to become the fourth-lowest-ranked player ever to knock off the top-ranked player at a major tournament.
After taking the second-set tiebreaker, Witthoeft broke serve in the opening game of the third set. However, Kerber rebounded to win the next four games before closing out the victory. The crowd then sang "Happy Birthday."
Kerber also needed three sets to win her opening match against Lesia Tsurenko on Ukraine.
In other action Wednesday, Venus Williams advanced to the third round.
The 13th-seeded Williams got by Stefanie Voegele 6-3, 6-2. Williams won the first three games of the first set to get control over the Swiss player ranked No. 112. Williams then charged out to a 4-1 lead in the second set as she was never threatened.
Voegele had five aces to four for Williams, but Voegele was hurt by five double faults.
The 36-year-old Williams, who has never won the Australian Open, has already improved on last year's showing in Melbourne, when she lost in the first round.
Alison Riske, a Tennessee resident ranked 42nd in the world, upset 20th-seeded Zhang Shuai 7-6 (7), 4-6, 6-1. Riske has never advanced past the fourth round of a Grand Slam event.
Eighth-seeded Svetlana Kuznetsova dispatched 17-year-old Australian Jaimee Fourlis 6-2, 6-1.
Eleventh-seeded Elina Svitolina of Ukraine also had an easy time advancing as she eliminated American Julia Boserup 6-4, 6-1 in her second-round match.
Boserup, who is ranked 119th, rallied from a 5-2 deficit to close the gap to 5-4 in the first set, but Svitolina won the 10th game at love on her serve to close out the set. Svitolina dominated the second set, winning the final five games of the match.
No. 24 seed Anastasia Pavlyuchenkova got past Russian countrywoman Natalia Vikhlyantseva 6-2, 6-2 in another second-round match.