SERENA Williams fired down an ace to win her 19th Grand Slam title and become the oldest Australian Open women's champion.

You would not have thought it by the way she bounced around like a kangaroo on the Melbourne court in celebration.

At the age of 33 years and 127 days, Williams yet again displayed her remarkable longevity by beating Maria Sharapova 6-3, 7-6 (7-5), in the final to move to within three major titles of the all-time record holder Steffi Graf.

In this kind of form, it is not beyond the realms of possibility that Williams could end up level with Graf this year. It was the German who last claimed a calendar Grand Slam in 1988 and you can be sure that Williams will have that in sight as one of the few remaining feats she still has to achieve in the sport.

"I would love to get to 22," said Williams. "Nineteen was very difficult to get to. Took me 33 years to get here. But I have to get to 20 first, and then I have to get to 21. There's so many wonderful young players coming up, so it will be a very big task. My goal was just to get to 19. That was my goal. I didn't think it would happen this fast, to be honest, but it feels really good."

There is extra intensity to the rivalry between Williams and Sharapova - it strayed into personal territory two years ago with comments about each other's love-lives - though their head-to-head record remains one-sided. Williams has now won 17 of their 19 meetings, with Sharapova last tasting victory against the American in 2004.

An early sign of the task facing Sharapova, as well as the tension, came in the opening game as she misfired wide with a backhand and then hit a double fault to concede the immediate break. Although she settled, rain interrupted play and there was a delay as the roof closed with Williams, who has been ill all week, coughing and spluttering as she walked back on to the court before going back inside to "throw up" as she later revealed.

It did not appear to have an effect on her tennis, however. Williams returned with intent, winning seven points in a row before breaking for the first set as she hit a cross-court backhand winner.

As one-sided as their record is, the contests between Williams and Sharapova, even those that finish in straight sets, generally do not follow that theme. An intense and thrilling second set ensued, during which there may have been as many shouts of "come on" from the two players as there were forehand winners.

It almost cost Williams at 3-3 as a premature shout after hitting a serve which she thought was not coming back lost her a point for a violation of the hindrance rule. She saved a break point in that game and later brought up her first championship point as Sharapova served to stay in the match, though it was saved by a blistering forehand winner by the Russian.

Sharapova saved a second match point in the tie-break and she was saved by the net cord on the third as Williams fired an ace out wide, dropped her racket in celebration before umpire Alison Lang called "let". There could not have been a better response as Williams turned round, hit another ace - her 18th of the match - which this time did clear the net to secure her first Melbourne title since 2010.

"It just felt so good," said Williams. "I've been through so much the past week. I really, really didn't expect to win. I didn't expect to be here this long. I was walking down the hall yesterday and I was thinking, 'Wow, I'm still in the tournament'. It's been a long time since I've been to the final here or the semi-final. It's been a long time coming."

Given the history between the pair, Sharapova's tribute to Williams in her on-court post-match speech was notably classy. The run of 16 straight defeats may never end but you can be sure the 27-year-old, with her deep reserves of fighting spirit, will give it her best shot.

"I haven't won against her many times," said Sharapova. "But if I'm getting to the stage of competing against someone like Serena, I'm doing something well. I'm setting up a chance to try to beat her and it hasn't happened.

"I'm not just going to go home without giving it another chance. That's just not who I am and not who I was raised to be. I'm a competitor. If I'm getting to the finals of Grand Slams and setting myself up to play a match against Serena, I'm happy to be in that position. I love the competition. I love playing against the best, and at the moment she is."