Angelique Kerber revelled as Rod Laver Arena sang her happy birthday but it was not all smiles for the top seed against Carina Witthoeft in the Australian Open second round.
Kerber, who turns 29 today, was made to dig deep for her 6-2 6-7 (3/7) 6-2 victory over her German compatriot, who led by a break in the decider, after winning nine points in a row.
There was an angry swish of the racket from Kerber, who for a short period lost focus before finally rediscovering her groove to book her place in round three.
She will now play world number 58 Kristyna Pliskova, the twin sister of Karolina, whom Kerber beat in the final here last year.
The world number one conducted the crowd, beckoned by on-court interviewer Sam Smith, as they chanted happy birthday after the match.
"I'm feeling here like home, so it's great to be always in Australia for my birthday," Kerber said.
"I just remember that I celebrated my 18th birthday at home, so that was a big party. But the rest, I was always here. It's nice."
Kerber will know, however, she must improve if she is to claim a third grand slam title, after making 34 unforced errors and enduring her second three-set match already in the tournament.
"I was doing I think a lot of mistakes like in the important moments," Kerber said.
"I was not finding my rhythm from the first ball so I know that I can trust my legs and can run for hours."
The left-handed Kristyna Pliskova will be a dangerous opponent too, having backed up a strong finish to 2016 by knocking out 27th seed Irina-Camelia Begu in the second round.
The connection with her sister and fifth seed Karolina adds extra spice but Kerber was unperturbed about seeing a similar face over the other side of the net.
"I don't know if it's weird," Kerber said. "One is right-handed and the other one is left so this is the difference.
"But I played once against her a few years ago and I know that she has a great serve, as well. I will look forward to playing against her."
Another answering questions about her age is 36-year-old Venus Williams, who is the oldest woman playing singles at Melbourne Park.
The American, who made her Australian Open debut in 1998 aged 17, cruised into the second round with a 6-3 6-2 win over Stefanie Voegele of Switzerland.
"I have to talk about this every interview," Williams said, smiling. "It's an honour and privilege to start that young - and to play this old."
An elbow problem, however, caused Venus to withdraw from the women's doubles, where she was due to play with sister Serena later on Wednesday.
"I was hoping to have the capacity to play both events here," said Venus, who plays China's world number 87 Ying-Ying Duan in the singles.
"But at this point I just need to be careful and try to maintain myself."
Ukraine's 11th seed Elina Svitolina wasted little time in advancing with a 6-4 6-1 victory over American Julia Boserup in 76 minutes on Margaret Court Arena, setting up a clash against 24th seed Anastasia Pavlyuchenkova.
Former world number one Jelena Jankovic converted four of her five break points en route to beating Germany's Julia Goerges 6-3 6-4. The Serbian next faces Russian eighth seed Svetlana Kuznetsova.
Two-times grand slam winner Kuznetsova eased past Jaimee Fourlis, beating the 17-year-old Australian 6-2 6-1 in an hour and 23 minutes at Margaret Court Arena.
There will be no fairy-tale run for last year's quarter-finalist Zhang Shuai as the Chinese 20th seed lost a tense two-hour, 45 minute-battle against American Alison Riske 7-6(7) 4-6 6-1.
Romania's Sorana Cirstea reached the third round of a grand slam tournament for the first time since the 2014 French Open after she beat Spanish 10th seed Carla Suarez Navarro 7-6(1) 6-3 in an hour and 33 minutes.
Canada's Eugenie Bouchard avoided back-to-back second round Australian Open defeats after she edged out China's Peng Shuai 7-6(5) 6-2 in an hour and 29 minutes.
