Williams, 36, should be back in the game soon. Her coach, Patrick Mouratoglou, told me that Williams, who gave birth to a daughter in September, was still planning to return to the circuit at the tournament in Indian Wells, Calif., in March.
But for now, Kerber, who turned 30 on Thursday, is the veteran champion working her way back in a sunlit place. She is also, after beating Sharapova, the last major singles women’s champion left heading into the round of 16. Kerber, a German, will face Hsieh Su-wei, a 32-year-old from Taiwan who is known best for her doubles prowess.
“Angie is already one step ahead of everybody else because nobody else knows what it’s like to win a Grand Slam,” said the Australian Rennae Stubbs, a television analyst and former player. “It’s bloody hard to do it. It’s nerve-racking and it’s stressful and it’s out-of-this-world different, and she’s already won two and won here and she’s playing great. She’s nails right now. She’s 2016 all over again.”
Sharapova, who will turn 31 in April, has farther to go to crank back her clock. Since returning last season from a 15-month suspension for an antidoping violation, she has not gotten past the fourth round in the two major tournaments she has played.
Once No. 1, she is closing in on the top 40 again. It would be quite a surprise if Sharapova, a Russian, were not one of the 32 seeds at the French Open, the next major tournament, which begins in Paris in May.
But her first serve was a liability on Saturday night, when she put just 38 percent into play. And though she generated plenty of her signature pace and acoustic fury, she was not nearly steady enough or acrobatic enough to keep up in this match. Kerber kept her off balance as a rule and countered her flat power effectively when Sharapova was able to deliver groundstrokes from more solid platforms.
“Angie knew it would be a tough one mentally, but if she plays like that, with aggression, she’s just a better player than Maria right now because of her movement,” Barbara Rittner, the German Fed Cup captain, said after chatting with Kerber as she warmed down from the match on a stationary bike.
Kerber’s new coach, Wim Fissette, was also part of the debriefing and is again having a quick impact on a new pupil. Fissette, a Belgian who started his WTA Tour coaching career working with Kim Clijsters, has since experienced success with Halep, Victoria Azarenka and Johanna Konta.
But he split with Konta last year, and when Kerber split with her longtime coach Torben Beltz, she recruited Fissette — in part because of his résumé and in part because he speaks German.
Kerber said Fissette was her first choice, and they are now off to a flying start. She has won 12 straight matches to start the season: four of them unofficial at the Hopman Cup team event and eight of them on tour.
“It’s a different voice,” Kerber said. “It’s a little bit different than with Torben, but you know, I think I needed the change, and that’s why I decided to change everything. I think it was a good decision to do it.”
She won the title in Sydney the week before the Australian Open after saving two match points in the first round against Lucie Safarova and then rallying to defeat Venus Williams in the second.
Stubbs was courtside for those matches.
“Venus was playing well, and Angie digs out the second set and then runs away with it and has not looked back after that,” Stubbs said. “It was like: ‘I remember how to win again. I have to dig deep, and digging deep wins me matches and then that gives me confidence and that reminds me I’m really good.’ And then everybody starts talking, ‘Angie’s back!’ ”
The risk, of course, is that Kerber starts hearing that chorus so often that she begins to think too hard again instead of just reacting and hustling and letting her beautiful game flow.
“I think she plays extremely well when she has a lot of matches behind her back,” Sharapova said. “I always thought she’s a confidence player.”