The Australian Open has reached the semi-final stage and, as usual, the women's event has thrown up a plethora of surprises along the way.
That said, there is no lack of quality in the final four, with two major winners in there and a US Open finalist.
We take a look at the match-ups and try to predict the outcomes.
Ashleigh Barty (1) vs Madison Keys
Head to head
Matches played: 3
Barty wins: 2
Keys wins: 1
On the face of it, this match looks a relatively straightforward one to call. It's on Barty's racket. However, don't be fooled by Keys' low ranking.
Keys has had a tough couple of years, but the pedigree is definitely there. She is a former US Open finalist and has reached at least the quarter-final stage of all four Slams in her career.
She has also been playing magnificently in Australia this month. Her clean-hitting power game from the back of the court works well in this climate, and she won the Adelaide International the week before the Australian Open.
Her run to the semis has been incredibly impressive too, with French Open champion Barbora Krejcikova and former Australian Open champion Sofia Kenin among her victims.
Madison Keys in focus
World ranking: 51
Highest ranking: 7 (October 2016)
Career titles: 6
Career majors: 0
Career W/L: 303/173 (64%)
Route to the semi-finals: R1 - Sofia Kenin (11) 7-6, 7-5
R2 - Jaqueline Cristian 6-2, 7-5
R3 - Wang Qiang 4-6, 6-3, 7-6
R4 - Paula Badosa (8) 6-3, 6-1
QF - Barbora Krejikova (4) 6-3, 6-2
For Barty the biggest danger appears to be the pressure. Australian women used to dominate this tournament but there has not been a home female winner of the tournament since Chris O'Neil in 1978.
That pressure has been too much for Barty before, although she says she feels better equipped to deal with it now than ever before.
She has certainly looked the part too. The world No. 1 is yet to be broken in the tournament and has dropped just 17 games in five matches.
One thing to bear in mind there, though, is she is yet to be really tested. She has faced just two seeds and no one from the top 20.
Ashleigh Barty in focus
World ranking: 1
Highest ranking: 1
Career titles: 14
Career majors: 2
Career W/L: 298/102 (74%)
Route to the semi-finals: R1 - Lesia Tsurenko 6-0, 6-1
R2 - Lucia Bronzetti 6-1, 6-1
R3 - Camila Giorgi 6-2, 6-3
R4 - Amanda Anisimova 6-4, 6-3
QF - Jessica Pegula
Planet Sport prediction: Barty in three
Danielle Collins (27) vs Iga Swiatek (7)
Head to head
Matches played: 1
Collins wins: 0
Swiatek wins: 1
Emma Raducanu has done many things since her astonishing breakthrough at the US Open last year, and taking the limelight away from Iga Swiatek is one of them.
Polish star Swiatek had a similar rise to prominence in 2020 when she won the French Open out of nowhere as a teenager.
She has struggled at the majors since then, but she's a player with genuine all-court pedigree. She was a Wimbledon junior champion on grass, a major winner on clay, and now has at least a Grand Slam semi-final to her name on hard.
She is yet to be truly tested at the Australian Open in fairness, but she's in the last four and is a strong favourite to go further.
Iga Swiatek in focus
World ranking: 9
Highest ranking: 4 (September 2021)
Career titles: 3
Career majors: 1
Career W/L: 149/47 (77%)
Route to semi-final: R1 - Harriet Dart 6-3, 6-0
R2 - Rebecca Peterson 6-2, 6-2
R3 - Daria Kasatkina (25) 6-2, 6-3
R4 - Sorana Cirstea 5-7, 6-3, 6-3
QF - Kaia Kanepi 4-6, 7-6, 6-3
Danielle Collins is one of those unremarkable yet effective players that absolutely no one wants to play. She's the classic banana skin.
She is the oldest semi-finalist at 28 years old, but while the others have all been in Grand Slam finals and the world top ten, Collins is still yet to break the top 20.
Collins has previous at the Australian Open, though, having also reached the semi-finals in 2019 before losing to Petra Kvitova.
Let's be clear here: Collins is very much the underdog, but no one will be underestimating her.
Danielle Collins in focus
World ranking: 30
Highest ranking: 23 (January 2019)
Career titles: 2
Career majors: 0
Career W/L: 185/109 (63%)
Route to semi-final: R1 - Caroline Dolehide 6-1, 6-3
R2 - Ana Konjuh 6-4, 6-3
R3 - Clara Tauson 4-6, 6-4, 7-5
R4 - Elise Mertens (19) 4-6, 6-4, 6-4
QF - Alize Cornet 7-5, 6-1
Planet Sport prediction: Swiatek in two