Serena Williams is getting ready for 2019 - and has big plans already as she prepares for the Australian Open.

That was the last Grand Slam she won, lifting the trophy in January 2017 while pregnant with daughter Olympia - and she's now aiming to win a record eighth title in Melbourne Park after she spent 2018 readjusting to on-court life.

"It truly makes me excited for what's ahead in 2019," she told the National.

"I always have crazy big goals but I like to keep them to myself. I think keeping them a bit of a secret helps me do the best I can."

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In 2018 she reached the final of Wimbledon as well as the US Open - an achievement of which she is proud.

"Honestly, I cannot believe the year I had," she said.

"I have to say I always expect the best from myself, but reaching two grand slam finals back-to-back was beyond my expectations."

Serena Williams (Getty)

She faces big sister Venus at the Mubadala World Tennis Championships this week, and is looking forward to resuming what she calls "the ultimate rivalry".

"I have never played anyone I respect more and am wary of more than her," the 36-year-old added. "We, year after year – and now I can say decade after decade – bring out the best in each other."

Serena made her comeback from maternity leave at the same event last year.

Venus is also excited about taking part in the tournament, as it is hosted in a part of the world she has long enjoyed visiting.

"I have had a lot of success in the Middle East and it is nice to come back to somewhere that you have done well at," she said. "It creates good vibes and gives you something to feed off so that is something I am looking forward to."