Showing yet again that playing surface matters less on the women's tour these days, the French Open semifinals on clay will be a repeat of last year's US Open semifinals on hard courts. And the one clay-court specialist in the mix, Italy's Sara Errani, is a heavy underdog.
The other three semifinalists, No. 1 Serena Williams, defending champion Maria Sharapova and Australian Open champ Victoria Azarenka, are familiar sights in the late stages of a major, a cross-generational group that has become the WTA's ruling trio over the past year and a half.
Maria Sharapova  vs. Victoria Azarenka 
Sharapova and Azarenka will take each other on in what is expected to be the more competitive of the two semifinals. They are just as well-matched in their games as they are in their shrieks -- a 7-5 record, led by Azarenka, with the Belarusian having the edge in recent Slam meetings but Sharapova showing more prowess on clay. Both are fierce competitors and hard hitters who will look to dominate points off the ground, but finding winners will be slightly more important for Sharapova as Azarenka is the faster of the two.
Whoever wins, a mixed prize likely awaits: a spot in the French Open final but also the likelihood of another meeting with Williams. The world No. 1 has an overwhelming head-to-head against both (13-2 against Sharapova and 12-2 against Azarenka), and she also defeated both convincingly in clay events leading up to the French Open.
Although the head-to-head numbers are depressingly similar for both, Azarenka has been more competitive against Williams than Sharapova. Azarenka has been able to force the 31-year-old American to play long points and pressure her in rallies.
So who wants to be Serena's biggest (non-)rival? That's the underlying subtext of this semifinal.
Serena Williams  vs. Sara Errani 
Facing an all-time great on the longest winning streak of her career, Errani can only draw encouragement from two things: First, that this match is on clay, her best surface, and second, that Williams was pushed for the first time this tournament in her quarterfinal match.
More discouraging will be the way Williams responded to being on the verge of going down two breaks in the third set against Svetlana Kuznetsova in the previous round. She roared back -- at times literally -- to finish with an intimidating display of hard hitting.
Can Errani draw any lessons from that match? Yes and no. Kuznetsova troubled Williams with spin, variety and power. Errani has the spin and variety, but struggles to generate power from her 5-foot-4 frame. That means she has little prospect of putting Williams away. The Italian's strategy will be to try to break Williams' rhythm and somehow get her to beat herself. But as Williams' quarterfinal match showed, she's determined not to do that.
All in all, Williams biggest remaining hurdle is mental. She has not won this title since 2002 and taken many difficult losses in between, including in the first round last year.
As she said a couple of weeks ago in Rome, "The lady in the mirror is the ultimate opponent for me."
The first task for the other three, meanwhile, is simply playing her close enough to make their presence felt as well.