Three of the four singles finalists will be known after what is set to be a scintillating day of play at the Australian Open.

Young American Sloane Stephens created perhaps the best story of the year’s first grand slam so far when she upset the favorite for the title and the defending Wimbledon and US Open champion Serena Williams in three sets.

But just 24 hours later, the 19-year-old will be back in action for the biggest match of her burgeoning career. Stephens will take to the court for her first ever grand slam semifinal against the top seed and defending champion, Victoria Azarenka.

As much as she matched Williams from the back of the court, perhaps most impressive about Stephens’s victory was the poise she exhibited to close out the victory. She will need all of that composure once more against Azarenka, who needs to claim the title to hold onto her No. 1 ranking.

As she takes on Stephens for the first time, Azarenka will be meeting her first seed of the tournament, although the Belarusian came through a stiff test against two-time grand-slam winner Svetlana Kuznetsova in the quarterfinals.   

Stephens certainly has the potential to cause another upset, but it is hard to imagine that she won’t have some sort of mental dip following her emotional triumph over Williams. Azarenka’s consistency is likely to prove too much.

Before that, Rod Laver Arena will witness a hard-hitting duel between Maria Sharapova and Li Na. Both players are in fine form having yet to drop a set to this stage. Sharapova’s record is even more imperious in losing just nine games—a record since the Australian Open went to 128 players 25 years ago.

The second-seeded Russian has won eight of the pair’s 12 matches, including the last three. Sharapova is certainly favorite to make her second-straight semifinal, but with Li looking back to her best, she may well, at least, lose her first set of the tournament.

Perhaps only an ardent David Ferrer fan will believe that the first men’s semifinal will be quite so competitive. Having come through an epic five-set duel with fellow-Spaniard Nicolas Almagro two days ago, Ferrer now faces the unenviable task of trying to end Novak Djokovic’s 19-match winning streak at the Australian Open.

Ferrer’s fitness is such that he is likely to recover relatively well, but his game just struggles to match up with Djokovic at his best. As well as the tireless 30-year-old can defend, Djokovic can do likewise and the Serbian can then counter with better weapons off of both wings.

Ferrer remains a credit to himself and the tour, but a first grand slam final is likely to continue to elude him.

Where to watch: The women’s semifinals at the Australian Open are scheduled to begin not before 9.30 p.m. ET on Wednesday, with the first men’s semifinal set to get underway at 3.30 a.m. on Thursday morning. Coverage of all the action will be provided by ESPN2, with a live stream available on ESPN3