Who is the greatest female tennis player of the Open era?
It is a question fans love to debate.
Of course, it is difficult to compare across eras, with technology and professionalism evolving since the Open era - which allowed professionals to compete alongside amateurs - began in 1968.
Is the number of Grand Slam wins what really matters? Serena Williams has won the most in the Open era - her victory in the Australian Open taking her to 23.
"Serena is the greatest of all-time because this era is so much more competitive than previous eras," says BBC Sport presenter Sue Barker, herself a former French Open champion.
Do you agree? From our shortlist, pick your 1-7 using our interactive tool - and if you still can't decide, Sue's analysis below might help.
We will announce your greatest on Monday, 30 January.
My greatest female champion
Pick your greatest champion by ranking the seven women who have won the most Open Era major titles.
Serena Williams - 23 titles in the Open era
Barker: "Serena has won 23 in an era which is so much more competitive than previous eras. The first, second and third-round matches at Grand Slams are more competitive than they used to be.
"The pace she generates, her serve is without question the greatest ever, and put that with her movement and her power, she pushes her opponents constantly on the back foot."
Steffi Graf - 22
Barker: "She is the greatest athlete that has ever played the game. Steffi made everything look effortless and incredibly graceful. The big forehand was her trademark.
"She was great for the game and we needed someone like her to take the game forward. However, I do feel she was in an era where she was not well challenged because Gabriela Sabatini went away and then so did Monica Seles after her stabbing. We never saw a great rivalry develop."
Martina Navratilova - 18
Barker: "Martina was the first person who changed the physical side of the women's game. While we all just went for a three-mile run, she started doing training off court - she did specific gym exercises and built up muscles which we hadn't seen before. She dominated, and the other players had to change.
"Her serve-volley was exceptional. I don't think there has been a better serve-volleyer in the women's game at the top level."
Chris Evert - 18
Barker: "She was mentally so incredibly hard. To try to get past Chrissie you knew you were going to suffer - you were going to run and run and run. She never broke down, she didn't make an error and played the big points so well.
"She didn't miss and never got nervous - that's why they called her 'The Ice Princess'. She never look flustered. Mentally she was incredibly strong and solid in every department."
Margaret Court - 11 (plus 13 before the Open era)
Barker: "Margaret was from a very different era. It is difficult to compare because it was a different game then - it wasn't a hard-hitting game. She was tall and had an incredible wingspan, she could almost touch either sideline! She had great reach so just trying to pass her was very difficult.
"However, most of her Grand Slams were won in Australia - and I sound a little bit disrespectful here - when it was only Australians playing it because no-one went there. I think the records that came later from the others were greater."
Monica Seles - 9
Barker: "Monica could have been one of the greatest ever if the stabbing had not happened. She was just beginning to get the better of Steffi.
"I feel tennis was robbed of that incredible rivalry because she was never the same player when she came back - which was totally understandable."
Billie Jean King - 8 (plus four before the Open era)
Barker: "Billie Jean is the greatest in terms of the whole sport, combining her Slam wins with everything else she has done off the court in terms of promoting the sport.
"Tennis is probably the best known women's sport because of everything she has done for the game. She was a great champion and moved the game forward."