"But being number one is something you should embrace and be proud of".
Caroline Wozniacki is also looking to defend her title after winning her first career major at this event a year ago.
"I was really impressed with Naomi, how she won the US Open and then went into Asia and made the Tokyo final", she said.
"There's no doubt that was a negative but there's no doubt that also previous year when you look at the bigger picture, the fact that she came back from having a child she was really nowhere near 100 percent and she still made the finals of Wimbledon and the US Open was incredible".
That loss left Williams, who also lost in the Wimbledon final a year ago, short of matching Margaret Court's marker of 24 grand slam titles, a record the American has another chance of equalling in Melbourne over the next fortnight. Williams reached the Wimbledon and US Open finals after her return past year but lost both, leaving her one short of Australian Margaret Court's tally of major singles titles.
In a new video for Allure, the 23-time Grand Slam champ demonstrated her skills as a manicurist, creating tennis-inspired nail art for a lucky model.
The shock diagnosis came after Wozniacki had returned to number one and taken her WTA tour title tally to 30 with victories not only in Melbourne, but also Eastbourne and Beijing.
Angelique Kerber of Germany celebrates defeating Belinda Bencic of Switzerland in the women's singles final during day eight of the 2019 Hopman Cup at RAC Arena on January 05, 2019 in Perth, Australia.
"In general, it's about her offensive game", Rittner told Deutsche Welle of the three-time Grand Slam champion who lost an agonising, breathless semi-final 9-7 in the final set to Halep in Melbourne a year ago.
The American, seeded 16, is gunning to match Margaret Court's record of singles majors and claim an eighth Australian Open crown.
The first Grand Slam of 2019 sees world number one Novak Djokovic aiming for his third consecutive slam title, and seventh Australian Open.
"I feel like if there's one thing I should be able to do it's draw a tennis ball", the Olympic gold medalist, 37, explained. "I enjoy Grand Slams the most", she said.
Serena Williams of the USA hits a backhand return during a training session in Melbourne on January 8, 2019, ahead of the Australian Open tennis tournament. "Don't be surprised if you hear about a part-time job I've picked up at a local nail salon", she wrote.