Germany's sports stars were overjoyed as Angelique Kerber gave her nation a first Grand Slam title since 1999 with victory at the Australian Open on Saturday.

A tearful Kerber, 28, stunned an errant Serena Williams to win Saturday's final and thwart the American top seed's bid to equal Steffi Graf's Open-era record of 22 Grand Slam titles.

In a huge upset, the seventh seed, who was born in Bremen to Polish parents, toppled the 34-year-old Williams 6-4, 3-6, 6-4 to win her first major title and become the first German Grand Slam champion since Graf at the 1999 French Open.

Former world number two Tommy Haas wrote "Awesome, congratulations! Angelique Kerber - Australian Open Champion 2016. Get used to hearing that", while her Davis Cup team-mate Andrea Petkovic jokingly proposed marriage: "Angelique. You're crazy. I want to marry you. COOOOONNGRATULAAAAATIONS!".

Germany's World Cup winning footballers also took to Twitter to express their delight.

"Yeeees! Congratulations on an historic win," wrote Germany captain and Manchester United star Bastian Schweinsteiger, while striker Lukas Podolski wrote" Yes!! Huge congraulations, what a match!"

Formula One driver Nico Rosberg simply wrote "Mega! Congratulations!", while Thomas Bach, president of the International Olympic Committee, said "Many congratulations! It was time. Steffi Graf's era was a good few years ago."

Anke Huber, the last German to reach the Australian Open final when she lost to Monica Seles in the 1996 final, was overjoyed for Kerber.

"What a crazy match, really well played and so well fought," Huber, 41, told SID, an AFP subsidiary.

"I am hugely delighted for Angie, she definitely deserved it."

Tennis stars from other nations also offered hearty congratulations.

The legendary Martina Navratilova, who won 18 Grand Slam titles in her career, praise both Kerber and Williams for their poise.

"I said before the match Kerber would have to play the match of her life to win - and she did," tweeted the 59-year-old Czech star.

"Wow - congrats! And Serena - what a gracious champion!"

And men's world number one Novak Djokovic, who faces Britain's Andy Murray in Sunday's final, heaped on his praise.

"What a final, girls! Great sportsmanship! Well done to both. Congrats to Angelique for her 1st Grand Slam," said the Serbian star.

German chancellor Angela Merkel also got in on the act, praising Kerber for keeping her composure to deliver the victory which so delighted her country's tennis fans.

"With this win, you have not only fulfilled your big dream, but, 17 years after Steffi Graf, also the millions of tennis fans hoping for a German win at a Grand Slam tournament," said Germany's leader.

"It was fascinating to see how unflinchingly, and with such strong nerves, you prevailed against arguably the best player in the world.

"I hope you enjoy this victory to the fullest in order to achieve many more successes."