Angelique Kerber has gatecrashed Serena Williams’ party to become the first German grand slam champion since the great Steffi Graf.

Kerber stunned the sporting world with a dramatic 6-4 3-6 6-4 Australian Open final triumph over the all-conquering world No.1 on Saturday night.

The three-set boilover was not only Williams’ first defeat in seven title matches at Melbourne Park, but also denied the American a place alongside Graf as the most successful women’s player in almost half a century of professional tennis.

Kerber is only the fourth player to conquer Williams in a grand slam final, joining the American’s older sister Venus, Russian Maria Sharapova and Australian Samantha Stosur.

As 28-year-old Kerber celebrated her magical breakthrough, Williams was left to lament another opportunity lost after succumbing to suffocating pressure for the second straight slam.

A shock semi-final loser to Roberta Vinci with a calendar-year grand slam within sight at the US Open, Williams again stumbled on Saturday trying to match Graf’s open-era record 22 singles majors.

Williams did her best to commit tennis suicide, making a staggering 46 unforced errors as Kerber dominated with awesome power and precision.

Mixing incredible forehand passes with deft backhand dropshot winners, Kerber surged to the biggest win of her career in two hours and eight tension-filled minutes at Rod Laver Arena.

Apart from being the first German since Graf at Wimbledon in 1999 to land a singles major, Kerber is only the second woman in the open era to secure the title after saving match point in the first round.

Kerber stood on the brink of defeat in her opener against Misaki Doi, but hasn’t looked back since, also taking out two-time champion and former world No.1 Victoria Azarenka en route to glory.

She will climb to a career-high No.2 in the rankings on Monday and also bank a cheque for $3.4 million.

Williams opened the match positively enough with a love service hold.

But the start merely masked the stress and nerves.

She made a succession of backhand errors to gift the German a break in the third game and it quickly became apparent this wouldn’t be a routine night at work.

In contrast, Kerber brought her A game from the outset, producing a brilliant backhand crosscourt winner en route to an ominous 3-1 lead.

Raising her intensity and stalking Kerber’s suspect second serve, Williams broke back for 3-3 with a scorching backhand return.

But she gave the break straight back with a wild forehand volley drive as her unforced error count continued to mount.

By the time Kerber held for 5-3 and then again to seal the opening set, Williams had racked up 23 mistakes to the underdog’s three.

But as Kerber edged towards a famous victory, the seventh seed coughed up consecutive double-faults to hand Williams a 4-2 buffer in the second set.

It was invitation enough for Williams to take the set and level the match up.

Ominously, Williams was eight from eight in deciding sets of grand slam finals.

Undeterred, Kerber retained her cool to break the top seed to love and surge to a 2-0 lead with a flurry of explosive forehand winners.

Williams fought back to 2-2 before Kerber reeled off three straight games to have the American on the brink.

Kerber faltered trying to serve out the match at 5-4, but finally prevailed as Williams dropped serve for a fifth time trying to stay in the contest.