Angelique Kerber, who had to save match point against the world No 64 Misaki Doi in her first contest of the 2016 Australian Open, finished the tournament in the most spectacular fashion by beating the incomparable Serena Williams in three wonderful sets here on Saturday night.

Kerber, seeded seventh, won 6-4, 3-6, 6-4 in two hours and eight minutes in front of an incredulous audience on Rod Laver Arena. It was the American’s 26th appearance in a slam final, the German’s first.

Watching Kerber methodically dismantle the best player in the world since her own compatriot, Steffi Graf, it was incomprehensible that Kerber might have fallen at the first hurdle to Doi, a player of towering anonymity, 11 days and six wins ago. Williams remains one slam victory short of Graf’s Open Era record tally of 22. If Kerber does not win another major, she will not forget this achievement, and this performance.

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Williams took defeat with the best of humour, although she had betrayed anxiety all the way through a fractious match. “I’m glad you had a chance to witness some great tennis,” she told the crowd. “You truly deserve it,” she told the winner, adding, “It was remarkably fun.” The latter sentiment was hard to believe.

Kerber, who moves to No2, is the first German to win this title since Graf in 1994. “Congratulations to Serena,” Kerber, welling up, said on the podium. “You are an inspiration to so many, an unbelievably great person. I was [almost] on the plane to Germany in the first match. I took my chance to be in the final, and I’m honoured. It’s my dream come true. Now I can say I’m a grand slam champion, and it sounds really crazy.”

Three truly horrific misses in a row – two to allow Kerber to take a 5-3 lead and the next one in the ninth game as she served to stay in the first set – told the story of the champion’s early exasperation, and it rarely eased.

The scream of frustration as a winner finally settled in the lines was a borderline late one – such as the “Come on!” yell that cost her a point when she lost to Sam Stosur in the US Open final in 2011. That was also the last time Williams lost the first set of slam final.

She held for 4-5, but her movement – especially at the net which she now raided indiscriminately – was heavy-footed, and Kerber, serving conservatively and playing safety-first last-ball tennis, welcomed three weary errors in the 10th game to take the first set.

Williams’s ball-toss was unreliable, her timing, from hand and off the floor, was ragged, and her demeanour was one of irretrievable despond. As in her shock loss to the lightly regarded Roberta Vinci in the semi-finals at Flushing Meadows last year when reaching for a calendar slam, she was off-balance and rocking on the back foot. Neither could she take advantage of her opponent’s ordinary serving, only 49% landing at first attempt in the first set.

Kerber’s return, meanwhile, was rock-like. In fact, pretty much nothing went right for Williams in the first 40 minutes or so – thereafter, apart from fleeting parity in the second set.

She held unconvincingly at the start of the second, but Kerber refused to buckle. Just as she was too steady for the British No1 Johanna Konta in their semi-final, so she stuck rigidly to her game plan against the best player in the world.

Williams finally found a chink in the German armour, breaking when Kerber hit long. It took her nearly an hour to hit her first ace, and she looked more relaxed after holding for 4-1. Kerber held to stay in the set, before Williams steeled herself, found an ace, and forced a loose forehand from Kerber to level at a set apiece.

The American continued to charge the net, regardless of the state of the rally, and Kerber passed her to break in the second game of the deciding set – then handed the break back immediately. There was little in the contest, but the Williams aura had disappeared, and she appeared reduced to gamesmanship in the changeover after the third game, when she went to the service line late and slowly, supposedly to unsettle her opponent, who was appearing in her first slam final at 28.

When Kerber passed her yet again in the fourth game, Williams turned to her box and mouthed, “I cannot put the effing ball away!” But she held for two-all.

Angelique Kerber's stunning Australian Open win over Serena Williams – in pictures Read more

The sixth game was pivotal. At 15-30, Williams was clipped in the shoulder off the net cord in another doomed raid, then hit wide for two break points, saving the first after a 19-shot rally, the longest of the game to that point, getting to deuce with an ace. An extended grind through deuce followed – Kerber drop-shotting Williams for the second time in the set, and Williams double-faulting again for a fifth break point. When the champion overcooked a forehand, Kerber led 4-2 and stood on the verge of a remarkable unexpected upset.

Pinned to the baseline after so many failed net raids, Williams was now a sitting duck for Kerber’s controlled, angled ground strokes and short work. After shoving a backhand well wide, Williams needed to hold to stay in the final, and came through despite a double fault and some shaky groundstrokes.

Kerber, serving for the title, went love-30 down, Williams hit long under no pressure, grabbed a break with a blistering cross-court forehand and looked hugely relieved when the German could not keep a forehand down. They were back on serve.

It was now about belief as much as class. Serving for survival again, Williams looked the less convincing until an ace got her to 15-30. She won two more high-grade rallies, but Kerber forced deuce off a woefully slow second serve, and got to match point when she pushed Williams into another weary forehand.

When the American’s final forehand drifted long, an extraordinary deed was done and the championship had a new and worthy champion.