NINETEEN years after they first played each other as professionals, Venus and Serena Williams will meet again tomorrow, with sibling rivalry and history on the line for both.

For the 35-year-old Serena, it is a chance to win a 23rd Grand Slam title, an Open era record, a seventh Australian Open trophy and regain the world No.1 ranking.

For the 36-year-old Venus, it will be her first Grand Slam final since 2009 and victory would give her an eighth Major title, her first since 2008, and make her the oldest woman to win a Slam in the Open era.

Life has come full circle for the Williams sisters, who began their professional rivalry on what is now the Rod Laver Arena in a second-round match here in 1998, a match Venus won 7-6 6-1.

Tomorrow, Serena will be the favourite but for the world No.2, who will pass Steffi Graf in the all-time list if she wins, the match is genuinely a celebration of their careers.

“I just feel like it's been a while,” said Serena, who crushed unseeded Croatian Mirjana Lucic-Baroni 6-2 6-1 in the semi-finals yesterday. “This probably is the moment of our careers so far, definitely for me.

“It's the one time that I really genuinely feel like no matter what happens, I can't lose, she can't lose. It's going to be a great situation.”

Second seed Williams was imperious as she crushed Lucic-Baroni in straight sets. The six-time champion has looked dominant in every round but has been trying to keep a lid on her emotions throughout the fortnight, refusing to talk about history.

For the second year in a row she has reached the final without losing a set and though she will not need reminding of last year’s defeat by Angelique Kerber, she looks in the mood to not let anything slip.

“I'm really proud of myself,” she said. “I feel like a lot of people were kind of writing me off, but it is what it is. I do best when I'm that underdog, I guess.”

The real underdog story, however, is in Venus reaching the final. When she announced in 2011 she had been diagnosed with Sjogren’s syndrome, an auto-immune disease that causes chronic fatigue and muscle soreness, many medical experts said she would find it hard to ever play professionally again.

But the elder Williams sister has battled on and in the last 18 months or so seems to have found a way to manage it, something Serena admires greatly.

“I was always stressed out and worried if she would be okay and be able to play,” she said. “I would see her practise, she'd practise so well. I always felt like when she lost I was almost surprised, kind of like, 'How did you lose, because you're doing so well?' At the same time I was like, 'Wow, it's amazing that you're even out here.'”

But Venus is not just here to make up the numbers and more than 19 years after her first Grand Slam triumph, she believes she can win.

“I had no idea what I was doing then,” Venus said. “But you’ve got to get to one before you get to another. Not all of us win our first one. It's a very difficult thing to do. I was a child. I'm still a child at heart. The stakes are different. It's history. It's a wonderful place to be at both times.

“It would be beautiful [but] I have to earn it – it's not a given. I'm going to do what I can to earn it.”