Serena Williams
Serena Williams may need to win her Australian Open semifinal to be sure of remaining world No. 1. Reuters

It’s already been decided that the Australian Open women’s final will be a United States-Russia affair, but there remains plenty of intrigue in discovering just who will be vying for the first Grand Slam title of the year. The first of Thursday’s semifinals will see Russian pair Maria Sharapova and Ekatarina Makarova face off, before American duo Serena Williams and Madison Keys vie for the right to meet the winner in Saturday’s final in Melbourne.

In both instances, it will be a case of a multi-time Grand Slam winner taking on a player looking to reach the final of one of tennis’ four major events for the first time. For the established names there is also the added pressure of the No. 1 ranking being on the line. Were Williams, the holder of top spot in the WTA rankings for 101 consecutive weeks, to lose her semifinal and her long-time rival Sharapova to best Makarova and go on to lift the title, the Russian would leave Australia on top of the world. Sharapova, though, is not taking anything for granted against the 10th seeded Makarova.

“Besides playing another Russian, I'm also facing an opponent that wasn't necessarily a favorite coming into that stage,” she said. “That's always a tricky situation because she's going to come into that match free and almost happy to be in that situation, and that's dangerous. You know, I haven't faced a lefty in this tournament yet. She's been using her lefty serve extremely well from what I've seen. But, yeah, I'll be looking out for that, work on a few things tomorrow, and be ready for that match.”

Sharapova produced arguably her best performance of the tournament to hit last year’s Wimbledon runner-up Eugenie Bouchard off the court in the quarterfinals. Indeed, since saving two match points to beat Alexandra Panova in the second round, the 2008 Australian Open champions has lost just 10 games.

But her opponent has yet to drop a set en route to what is Makarova’s second Grand Slam semifinal and second in succession after her run at the U.S. Open last year. The 26-year-old has the odds stacked against her to go one further this time around, having taken just one set off Sharapova in their five previous contests.

There is no such form guide for the second semifinal. The 33-year-old Williams has never met her 19-year-old compatriot Keys in a tour-level event. Keys has, though, got very much recent experience of taking on a Williams.

In the quarterfinals, which was already two rounds further than she had ever gone before in a Grand Slam, the Illinois native got past Serena’s sister Venus in three sets. After her heavy hitting proved too much for Venus in the opening set, Keys was forced to go through the pain barrier to get the win having suffered a similar injury to the left abductor problem that forced her to pull out of Wimbledon last year. Keys is not helped by this being the only rounds in the tournament between which she won’t have the luxury of a day’s rest, but she remains hopeful that it won’t spoil the experience of her first Grand Slam semifinal.

“It still hurts,” she said after her quarterfinal win. “[I’m] definitely going to be getting some treatment on that. Hoping I can get it as good as possible for tomorrow. I think it's one of those things where all of us have dealt with injuries before. It's one of those things where it's probably going to hurt, I'm probably going to have tape on it, but I'm just going to do my absolute best and enjoy the moment.”

Even if Keys conquers her injury, however, Serena poses a formidable obstacle. The 18-time Grand Slam champion has won the Australian Open on all five occasions in which she has gotten past the quarterfinals and, despite battling illness, produced her best tennis of the tournament to date to breeze past Dominika Cibulkova in the last round.

After the women’s semifinals take center stage during the day, the first men’s semifinal highlights the evening session on Rod Laver Arena. And, while they don’t share the same nationality, there is a more than strong enough link between Andy Murray and Tomas Berdych. Up until the end of last season, Dani Vallverdu, a friend of the Scot since their teenage years, had been a constant presence in Murray’s camp through three different coaches. But then they split, they insist amicably, with Murray keen to fully embrace the methods of coach Amelie Mauresmo.

Vallverdu was soon appointed as coach of Berdych, who was also looking to shake things up after being a long-time member of the top 10 but failing to break through and win a Grand Slam. And the Czech seventh seed paid tribute to his new coach after ending a 17-match losing streak against Rafael Nadal to topple the Spaniard in straight sets in the quarterfinals.

Murray, though, has progressed serenely through the tournament as he looks to return to his first Grand Slam final since winning Wimbledon 18 months ago. In the last eight, the sixth seed quelled rising star and home favorite Nick Kyrgios in straight sets. And he is calm about going into a semifinal with his former mentor in the opposing corner.

“I don't know, maybe I'll find it weird on the day,” Murray said. "But it's just something that you deal with as a player. My goal isn't to beat Dani; my goal is to beat Berdych. So I don't think about that in the next days. We'll see how the match plays out and what the tactics are and stuff. But, you know, I also know what Dani thinks of Berdych's game because he's told me, so it works both ways.”

Schedule: Sharapova and Makarova are due to take the court not before 9:30 p.m. EST, followed by Williams and Keys. Murray and Berdych are set to get underway at 3:30 a.m. EST.

TV channel: ESPN2 from 9:30 p.m. and ESPN from 3:30 a.m.

Live stream: ESPN3, Watch ESPN