Going into the final, Williams was a heavy favorite - not only did she already have 21 Grand Slam titles to her name, including six Australian Opens, but Kerber was playing the first Grand Slam final of her career, and Williams had won the pair's last four meetings, all of them in straight sets as well.
Kerber didn't really read the script, though. She was just too solid in the first set, drawing 23 unforced errors from the Williams racquet and breaking twice to take it, 6-4. Williams rebounded well - she powered to a 4-1 lead in the second set, eventually taking it, 6-3, to push the match to a third.
Kerber never stopped believing, though. She built a 2-0 lead in the third set, and after Williams caught up to 2-all, Kerber raced out to a 5-2 lead. The No.1-seeded Williams very nearly caught up again - she won the next two games and was a point away from 5-all - but the No.7-seeded Kerber had just enough gas left in the tank to finally close the 21-time Grand Slam champion out, 6-4, 3-6, 6-4.
Kerber not only walks away with her first major, but she's just the second German woman in the Open Era to win a major, after Steffi Graf, who won 22 majors in her legendary career. She also preserved Graf's Open Era record - Williams would have tied it had she won the title on Saturday night.
There's another big first - having saved match point in her first round against Misaki Doi here, Kerber's the first woman in the Open Era to win a major having saved a match point in the first round.
She'll also surge to a new career-high ranking of No.2 now, behind, of course, Williams.
Williams was first to take the microphone at the trophy ceremony. "Angie, congratulations. You really deserved it - let me be the first to congratulate you," she said. "I hope you enjoy this moment."
And with a great big smile on her face, Kerber followed Williams to the podium.
"First of all, I would like to say congratulations to Serena," the German said. "You're really an inspiration for so many people and young tennis players. You've created history. You're a champion. You're also an unbelievably great person. So congratulations to everything you've already done.
"When I was match point down, I actually had one leg in the plane back to Germany. I got a second chance, and I took that chance to be here in the finals to play against Serena. I'm really honored to be in this final and to win it - my dream came true tonight," she said, fighting back tears of joy.
"My whole life I was working really hard, and now I'm here, and I can say I'm a Grand Slam champion, and it sounds really crazy," Kerber added. "These have been the best two weeks of my life."
? WTA (@WTA) January 30, 2016