Martina Navratilova has backed Serena Williams to create history by sweeping to a calendar year grand slam.
The tennis legend described Williams as the greatest player of her generation and said "if anyone can, Serena can" achieve the holy grail of winning all four major titles in the same year.
"We know that Serena at her best is better than anybody else out there, if for no other reason than her serve. It sets everything up," Navratilova said at Melbourne Park.
"She's strong and she's solid. She very confident and very focused right now. In the past, there might have been times when you could catch her off guard, but not these days.
"She's been very focused since she lost at the French last year. She's very motivated. She's a dictator."
Steffi Graf was the last woman to win the Australian Open, French Open, US Open and Wimbledon in the same season, way back in 1988.
No man has claimed the grand slam in the Open era, with even Roger Federer, Rafael Nadal and Novak Djokovic all falling one short in their finest seasons.
The last male to do it was Australia's Rod Laver in 1969.
The closest Williams has come was in 2002-03, when she held all four majors consecutively for the so-called "Serena Slam". It was close, but not quite the feat that stands higher than any other in the sport.
Ahead of Williams' quarter-final against American teen Sloane Stephens, Navratilova said the grand slam was "definitely possible" this year as long as luck was on her side.
"We have seen what can happen physically. She hurt her ankle in her first match. She hit herself in the face with her racquet," she said. "There is a lot of luck involved. You can eat some bad fish and next day, you can't walk. It's 28 straight matches you have to win, but I do believe that if anybody can do it, it's Serena.
"The way she's playing now, she's capable of it."
Williams recovered from a first-round loss at the French Open last year to win Wimbledon and the US Open, leaving her with 15 major titles and within range of the 18 held by Navratilova and Chris Evert.
"In tennis terms, Serena is still very young," Navratilova said.
"At her age, I think I had played twice as many matches. She has young legs at 31, which should be helpful. The way she plays, not many of her matches are too physical or go too long.
"She is physically so imposing she can dominate matches. It does get harder after you reach 30, but Serena is Serena.
"She has taken tennis to another level. If she is fit and motivated, which she clearly is at the moment, and it's hard to see anyone beating her all year."
Navratilova, 56, who has 31 doubles and 10 mixed doubles majors along with her singles crowns, was described by another former world No1, Billie Jean King, as "the greatest singles, doubles and mixed doubles player who's ever lived".
Navratilova said she would have fancied her chances against Williams if they had played in the same era. "People ask me if I think I could have beaten Serena," Navratilova said.
"I say, 'Do you think I could have beaten Justine Henin?' They say, 'Yes.' I say, 'Well, Justine beat Serena, so there's your answer.'
"I think I would be able to handle her pace. Serena has a harder time playing people who are fast, and I was pretty fast in my day. I think I would be able to neutralise her power."