MELBOURNE (AFP) - Serena Williams will take aim at Steffi Graf's Open-era record of 22 Grand Slam singles tennis titles on Saturday, when she plays the Australian Open final against Germany's Angelique Kerber, who is hoping to pull off a major upset.

The world No. 1 is the overwhelming favourite to win her seventh crown at Melbourne Park and match Graf's career Grand Slam haul, warning she is in even better form than last year, when she won three major titles.

"I think I'm playing better. I know my practices are better. Hopefully I'm playing better," Williams said, adding that at 34 and with the clock ticking, she is making the most of every minute on court.

"I kind of relish every win and every final and every match now. I think maybe in the past I didn't as much. I was just like going through the motions.

"Even though I was super-excited, I just feel like now it's even more exciting."

The American has been in imperious form at the season's opening Slam, easily dispatching the likes of Maria Sharapova and Agnieszka Radwanska, but seventh seed Kerber believes she can spring a surprise.

"She will go out there to win her next Grand Slam. I must be ready to take the challenge to play against the best player right now," said the German, ahead of her first Grand Slam final.

"She's the world No. 1, she's the champion, she's won everything. I have actually nothing to lose.

"But still I will go out there to try to challenge her, playing good tennis. I know that I won against her once, so I can beat her. But I must play my best I can play."

Williams, the top seed, has a 5-1 record against Kerber and has won their last four matches, with her only loss against the German coming at Cincinnati in 2012.

That loss is still fresh in her memory, and she is taking nothing for granted against a player who won four tournaments last year - and credits her new-found form to inspirational words from Graf, her fellow German.

"I thought she played unbelievable in that match. That's something that I'll never forget," said Williams.

"I just remember her serving really well, her moving well, her being determined to win that.

"I think from then on out I've been really focused that she's someone that I really, you know, and everyone, has to take very serious."

At stake for Williams is more than just another Grand Slam title for her collection.

Victory will put her equal with Graf's Open-era record that has stood since the German won her 22nd and last major title at the French Open in 1999.

That was the same year Williams, aged 17, won her first Grand Slam crown at the US Open. It has taken half of her lifetime to now be on the verge of equalling the German great.

"I definitely block it out," she said, of her thoughts about reaching the milestone.

Australian Margaret Court holds the all-time record of 24 Grand Slam singles wins.

The penultimate day of action will also see new men's doubles champions, in a final which will immediately follow the women's title fight on Rod Laver Arena.

Brazil's Bruno Soares and his British partner Jamie Murray, brother of single's finalist Andy, face off against Czech veteran Radek Stepanek and Canadian Daniel Nestor.

Both pairs are bidding to become the first doubles team to win a Grand Slam in their first major together since Vasek Pospisil and Jack Sock at Wimbledon in 2014.

Whoever lifts the trophy, it will be the fifth straight year there has been a different doubles champion, with America's Bryan brothers the last team to successfully defend the title in 2011.