MELBOURNE, Australia - Australian Open semifinal competitors include Grand Slam final four regulars Victoria Azarenka, Maria Sharapova and Li Na and emerging star Sloane Stephens, who is having a breakthrough tournament and will have to return to the court a day after recording the biggest win of her career.

Thursday, Semifinals
Rod Laver Arena
[2] Maria Sharapova (RUS #2) vs. [6] Li Na (CHN #6)
Head-to-head: Sharapova leads 8-4
The first semifinal will see the two players yet to drop a set this fortnight square off. However, Maria Sharapova has surrendered just nine games, an Australian Open record since the event went to a 128 draw in 1988, while Li Na has dropped 31. On top of that, Sharapova has spent by far the least time on court of the semifinalists - 5 hours, 15 minutes.

A victory over Li would be Sharapova's 40th at the Australian Open, where she has reached the semifinals five previous times - the most of any major for her. However, Li has quite a few pleasant memories here too, having reached her first Grand Slam final four in Melbourne in 2010 and first Grand Slam final in 2011.

The series between the two has been back-and-forth, with Sharapova winning the first five, losing the next four and winning the next three. She is 3-1 against Li at majors and 5-1 on hardcourts. Sharapova has a chance of returning to No.1 in the world if she wins this match; Li has assured herself of a return to the Top 5 regardless of how she does the rest of the tournament.

[1] Victoria Azarenka (BLR #1) vs. [29] Sloane Stephens (USA #25)
Head-to-head: First meeting
Riding a 12-match winning streak in Melbourne is 2012 Australian Open champion Victoria Azarenka. She will need to defend her title in order to hold onto her No.1 ranking, and the latest hurdle in that quest is the first seed she has played all fortnight - Sloane Stephens.

"I think Sloane is a very, very talented girl," Azarenka said. "I think over the last couple years, you can see her development as a tennis player. Her game has come together. She's an all-around player, very competitive.

"She has good potential. It's just a matter of her getting all those details in place and really wanting to achieve great things."

Stephens' dramatic upset of World No.3 Serena Williams in the quarterfinals on Wednesday was her first Top 10 and Top 5 win and put her into her first Grand Slam final four. It also made her the first teen to reach a Grand Slam semifinal since Yanina Wickmayer and Caroline Wozniacki at the 2009 US Open and the first American teen since Williams at the 2001 US Open. She is assured of making her Top 20 debut on the new rankings and of overtaking Varvara Lepchenko as the second-highest ranked American behind Williams. Her encounter with Azarenka will be her second meeting with a World No.1, having fallen to Caroline Wozniacki at Indian Wells in 2011.