(2) Maria Sharapova vs. (3) Victoria Azarenka
Head to Head: Azarenka leads 7-5

The baseline becomes a measuring stick when Victoria Azarenka and Maria Sharapova face off. Both women are aggressive baseliners who willingly give up ground about as often as the Mona Lisa flashes a frown.

Two former No. 1s are at their best straddling the baseline and driving piercing shots into the corners of the court to push opponents into pursuit. So what happens when two control freaks collide? When Australian Open champion Azarenka plays reigning Roland Garros champ Sharapova, the woman commanding the center of the court, taking the first strike, serving with authority, and keeping calm will advance to the final. The third-ranked Vika has won seven of 12 matches with Maria, though the second-ranked Russian has prevailed in both of their clay-court meetings.

Sharapova showed the value of short-term memory loss and a strong will as she shrugged off a first-set shutout to score a 0-6, 6-4, 6-3 quarterfinal comeback over former No. 1 Jelena Jankovic—the first time in her career that she’s stormed back from an 0-6 opening set to win a match. Sharapova has won 16 of 17 clay-court matches she’s played this season, with her lone loss on dirt coming to Serena Williams in last month’s Madrid final. Since that setback, Sharapova has ran off 14 of her last 15 sets in advancing to her 17th Grand Slam semifinal.

As her quarterfinal progressed and her confidence grew, Azarenka increasingly stepped inside the baseline and stung shots into the corners, taking five of the final six games in a 7-6 (3), 6-2 victory over Maria Kirilenko to reach her first French Open semifinal. Vika has broken serve 31 times in five tournament wins and rolls into this match with a 27-2 record on the season. If Azarenka wins the battle of court positioning and continues to rip returns and serves with the control she’s exhibited so far, she will be very tough to stop. Azarenka has taken pace off her first serve in pursuit of a higher percentage; she’s served nearly 70 percent or better in four of five matches, including 78 percent in the quarterfinals.

Since both women are snipers on return, there could be a series of service breaks at the outset as each tries to establish serve. Winning backhand exchanges have been important in their past meetings, as both can crush the backhand cross-court and both can take their two-handers up the line. Timing, depth and confidence are key here: When you swing as big as these two do, you’ve got to time the ball extremely well to minimize mishits and maintain the length of shots, as both can punish mid-court replies. Sharapova has done a fine job regaining her form when she loses her range in posting a 35-4 record in 2013, but she’s up against one of the few women not named Serena who can hit her off the court.

Azarenka knows she has the game to beat Sharapova and should not be short on confidence: She’s won both of their Grand Slam meetings, including a 6-3, 6-0 dismantling in the 2012 Australian Open final. But Sharapova is the more successful clay-court player—five of her last six titles have come on dirt, while Azarenka has just one career clay title to her credit. The forecast calls for a chance of isolated thunderstorms, and if wind becomes a factor it should aid Azarenka; Sharapova has a higher ball toss that can stray in a stiff breeze and she is the flatter hitter, working with less margin for error over the net.

Only three of the 12 matches these two have played have gone the distance, with Sharapova winning the first two and Azarenka prevailing in the U.S. Open semifinals last September. Nine of their 12 encounters have gone to the woman winning the first set. Both are exceptional ball strikers capable of cracking return winners and building cumulative pressure with their cross-court drives. Sharapova overcame a horrific start against Jankovic and knows it will be very tough to play catch-up against Azarenka, who is typically a strong front runner.

This shapes up as a toss up of first-strike tennis, but I’ll favor Sharapova based on her past clay-court success, her expansive reach, and her drive to return to the Roland Garros final for the second straight year.

The Pick: Sharapova in three sets

(1) Serena Williams vs. (5) Sara Errani
Head to Head: Williams leads 5-0

Two world No. 1s face off for a place in the French Open final. Top seed Serena Williams rides a career-best 29-match winning streak into her semifinal with doubles world No. 1 Sara Errani, who shattered an 0-28 glass ceiling against Top 5 opponents by beating Agnieszka Radwanska, 6-4, 7-6 (6), to reach her second straight French Open semi.

This is a severe stylistic contrast: Errani extends points, Williams exterminates them. The two most essential shots in tennis are the serve and return, and Williams is more dangerous in both departments. Errani, the 2012 singles finalist and doubles champion, spins her first serve in as a point-starter; her average second-serve speed in the quarterfinals was about 67 M.P.H. If Sara sends sub-70 M.P.H. serves at Serena, any hope of consistently holding serve may require a visit to Lourdes. The 2002 champion is averaging about five breaks per match.

What more can be said about Serena’s serve? This: Throughout the tournament, she has taken pace off and effectively hit the slider wide on the deuce side to set up the first strike. That’s a smart play against the 5’4” Errani, who has restricted reach and can be vulnerable when stretched.

These two met in the Madrid semifinals last month, with Williams prevailing, 7-5, 6-2, extending her unbeaten edge over Errani and giving her experience against the heavy topspin—and enormous energy—the inexhaustible Italian brings to court.

“We had a pretty tough match in Madrid—I’m glad I played her in Madrid because I know she’s here to play and she’s here to compete,” Williams said. “She’s so serious. I can be ready for that.”

Picking up the pace is the immediate challenge for Errani, who defeated lighter hitters Carla Suarez Navarro and Radwanska in succession. Now, she faces the explosive power of the woman who hit her off the court, 6-1, 6-2, in the U.S. Open semifinal last September. Furthermore, the conditions in Paris have dried and the terre battue is playing faster than the drizzly first week, which favors Williams. If Serena comes out slugging with the precision and menace she’s shown throughout the tournament—this world No. 1 has dropped just three games total in the opening sets of her five tournament wins—Errani is at risk of being blown away. It’s essential she gets off to a fast start and hang with the heavier hitter, as Williams owns a 40-1 French Open record when winning the first set.

“It’s for sure going to be very difficult, because she’s very strong, and physically she’s an incredible athlete,” Errani said. “She has a lot of power and it’s never easy to play against her. But maybe clay is a bit better than the other surfaces for me.”

Sometimes, quick-footed counter-punchers who can change up spins can coax errors from Serena on clay; Anabel Medina Garrigues did so in winning a set from her in Madrid weeks after Jankovic extended enough points to do the same in the Charleston final. Conventional wisdom suggests Errani drop back behind the baseline and use her whipping topspin and defensive wizardry to try to drag Williams into long rallies and frustrate the bigger hitter into mistakes and malaise.

But the problem with playing prevent defense and trying to softball Serena into imploding is that Williams plays with plenty of margin and hits such a heavier ball that she can detonate points quickly—or, choose to play cross-court combinations and use her controlled power to run the Italian corner-to-corner.

If Serena avoids the stagnant footwork that sometimes strikes when she’s nervous and is quick off the mark, she is very difficult to drop shot. Errani must mix it up, play some high loopers when pushed out of position to buy herself recovery time, use her slice backhand to try to pull Williams forward—then try to beat her with the lob over the backhand side—use her net skills to occasionally attack, play off-pace angles short, and sometimes drive deep topspin down the middle to tie up Serena.

And, most likely, Errani must hope Williams tightens up. While Serena has had a couple of meltdowns in majors—against Kim Clijsters at the 2009 U.S. Open and against Virginie Razzano at the 2012 French Open—she showed her strength and will in fighting off break points and hitting brilliant shots under pressure in the third game of the deciding set to spark her quarterfinal comeback over Svetlana Kuznetsova.

Unlike last year when she pinched back tears on court during her first-round loss, Williams has channeled her emotion into action and turned up her game and intensity when tested at Roland Garros. Serena even celebrated her quarterfinal win by speaking French in the post-match interview, and closed imparting a sweaty hug to former French standout and TV interviewer Cedric Pioline. Look for the part-time Paris resident to embrace the challenge and reach her first Roland Garros final since 2002.

The Pick: Williams in two sets