Victory against the indomitable Serena Williams in January at the Australian Open defied all expectations; the 28-year-old German had never even reached a grand slam final until that day.
But now, as the season's end draws near, Kerber is proving it was more a watershed moment than a flash in the pan.
Overcoming Karolina Pliskova to take her maiden US Open title on Saturday
, Kerber became the first female player other than Williams to win two majors in a season since Justine Henin in 2007.
"It's been an incredible year so far -- the best of my career," Kerber tells CNN's James Blake.
"There have been a lot of up and downs, so that's why I'm really happy to be sitting here now as a grand slam champion and world No. 1."
A new German No.1
The women's game has been in the thrall of Serena for so long that even the slightest blip seems to signal a changing of the guard.
Williams' 186-week reign as the undisputed WTA number one finally came to an end after an uncharacteristically quiet showing in Rio preceded a second consecutive US Open semifinal defeat.
To discredit such performances serves only to illustrate Williams' greatness -- but the fact she surrendered her berth so soon after drawing level with historic rival Steffi Graf's record of consecutive weeks at the top will not have escaped the American's attention.
A new German leads the way today -- for just as Graf has provided a target for Williams, she has proved an inspiration for her compatriot Kerber.
"It means a lot to me because I've been working so hard in the last few years," says Kerber. "To see that hard work paying off is very good.
"It's just amazing. To win my second Grand Slam here -- especially in New York -- is really special for me."
But despite famously celebrating her Australian Open win with a dip in the Yarra river
, Kerber has no intentions of following a second slam with a second swim.
"We are not jumping in the river here," laughs the German, despite the proximity of New York's Hudson River. "I think [Yarra ] was enough.
"We will go for a drink tonight, a nice dinner ... and let's see what else. For now I have no idea what the plans are!"
One thing's for sure -- having broken through the glass ceiling in the women's game, Kerber has no intention of coming back down to earth.