World number one Angelique Kerber gave herself the perfect birthday gift Wednesday by reaching the Australian Open third round, but she had to work hard against fellow German Carina Witthoeft.
The defending champion, who turned 29, battled through 6-2, 6-7 (3/7), 6-2 and will next face Czech Kristyna Pliskova, the twin sister of fifth seed Karolina Pliskova.
The prospects looked bleak for the unseeded Witthoeft, who has twice lost to Kerber at Wimbledon including an embarrassing 6-0, 6-0 'double bagel' in 2015.
Witthoeft has never beaten a top 10 opponent but she showed far more fight than at the All England Club, with Kerber taken to three sets for the second match in a row.
The top seed said she struggled with the sun in her eyes at times and admitted to too many silly mistakes.
"I was doing I think a lot of mistakes in the important moments. But at the end, I'm happy that I won the match," she said.
"It was not so easy. The conditions were a little bit difficult today. And I was a bit too defensive."
Kerber stunned Serena Williams in the final last year and also went on to win the US Open, dethroning the American as the world's top ranked player.
She is not only defending a major title for the first time but also playing her maiden Grand Slam as top seed, admitting she is still getting used to dealing with the extra pressure.
"To have this pressure is a privilege. It's completely new for me, but I'm doing well. I'm just trying to enjoy it," she on court, before the Rod Laver Arena crowd sang "Happy Birthday".
"I am getting older... I think I will have a great day today," Kerber added.
The top seed came out of the gates at full pelt, breaking the 21-year-old in the first game when her opponent netted a backhand.
Ranked 89, Witthoeft was pushed around the baseline by the left-hander but some unusually wild shots from Kerber handed her break opportunities, one of which she grabbed to level the match.
It was an aberration as the birthday girl immediately broke back, before turning up the heat to score another break and then holding serve to take the set.
Bidding to be the first woman to defend her Australian title since Victoria Azarenka in 2013, Kerber had an indifferent lead-up to Melbourne with early exits in Brisbane and Sydney this month.
She has slowly been improving as he works her way deeper into the Australian Open and towards a potential quarter-final against Garbine Muguruza, with Williams seeded to meet her in the final.
She came out firing in the second set, ambushing Witthoeft for an early 2-0 lead. But she lost focus and her countrywoman made the most of it, breaking back with some pinpoint shots from the baseline.
The set turned into a slug-fest and Kerber succumbed to the pressure in the tiebreak, firing blanks on her serve which allowed Witthoeft to win six points in row and take the set.
Kerber was rattled and lost her opening service game of the third set to love, but she quickly regrouped as the crowd got behind her to break back.