Victoria Azarenka has warned all Australian Open title-hopefuls that Serena Williams will be desperate to add to her grand slam tally.
Williams suffered defeat in the 2016 Melbourne final and was dumped out of her most recent slam at the semi-final stage, when Karolina Pliskova sprung a shock at the US Open.
But Azarenka, a two-time winner of the year's first major, knows the American has what it takes to come out fighting.
The Belarusian told Omnisport: "I think she always has a chance. She will be the favourite no matter what because she has the past experience where she has lost matches before and come back and played amazing.
"Knowing how I played against her, the previous result didn't matter – she knows how to overcome it.
"With so many years of experience and great results I would never count her out, no matter what."
Williams, who faces Belinda Bencic in the first round in Australia, saw her record-equalling 186-week run at number one ended by Angelique Kerber last year, while Andy Murray is also a newcomer to the top spot in the men's game, overtaking Novak Djokovic.
And Azarenka feels it is a good thing for the sport to have a change at the summit.
"You can't deny the greatness of both players and the dominance they've had over the years," the 27-year-old said of Williams and Djokovic.
"But someone like Andy Murray who is right there, he was in the finals, the semis, he wasn't far away.
"He really turned it around and made himself the leader and he proved it throughout the whole year. I think it's great first of all for British tennis to inspire more people to play.
"For Angelique it's also exciting and brings the spark for competition and more interest of players to become number one. They see someone else has done it that maybe not many people predicted would, so I think it's pretty exciting."