When the Monterrey draw appeared, the possibility of a semifinal between Ana Ivanovic and Caroline Wozniacki intrigued.  Both women have held the No. 1 ranking, while both have fallen sharply after reaching that peak.  Ivanovic soared higher than Wozniacki, who never has won a major title, by triumphing at Roland Garros six long years ago.  But she also fell lower than the Dane ever did, dropping outside the top 50 during the slump that followed her breakthrough.

Flashes of their former selves have burst from both Ivanovic and Wozniacki at times this year.  Ivanovic already has won a title and defeated world No. 1 Serena Williams at the Australian Open, where she reached the quarterfinals.  Wozniacki arrived in Monterrey from an encouraging quarterfinal run in Miami, where she gave world No. 2 Li Na a stern test.

Sustaining form from week to week has proved a daunting challenge for these former No. 1s.  Thus, it was uncertain that this Monterrey semifinal would take shape despite the top-four seeds that they held.  And neither woman has dominated a modest field that they would have devoured in their primes.  While Wozniacki dropped the first set to Karolina Pliskova on Friday, Ivanovic regrouped from losing a 6-0 set to Magdalena Rybarikova.  (It was the first time that she rallied from that position since the 2008 Australian Open against Daniela Hantuchova.)  The Serb also rallied from losing the first set of her first match in Monterrey to Agnieszka Radwanska's sister, Urszula.

Ivanovic and Wozniacki are ranked consecutively at No. 13 and No. 14, which feels appropriate in view of their parallel career arcs.  Just as even is their career head-to-head on hard courts.  They have split their four meetings on this surface, where they have not met in two years.  All four of those meetings, and a fifth on clay, ended in straight sets, and the wins for each woman came at tournaments where the winner often has fared well.  While Ivanovic prevailed at the Australian Open and Indian Wells, both comfort zones for her, Wozniacki triumphed at two events where she has won titles in Dubai and Beijing.

This matchup pits the first strikes of Ivanovic on serve, return, and forehand against the superior movement and consistency of Wozniacki.  Since the courts of Monterrey have played quickly this week, the Serb might hold an edge.  But the mental component may prove just as important, and that area might favor Wozniacki.  The Dane should have more confidence than she has enjoyed in several months following her Miami quarterfinal run.  

The former No. 1 who wins this semifinal will enter the final as a heavy favorite.  In the other Monterrey semifinal, the 43-year-old Kimiko Date-Krumm faces first-time WTA semifinalist Jovana Jaksic, a compatriot of Ivanovic.  Both women deserve high marks for reaching that stage, but neither is a player of Ivanovic's or Wozniacki's level at this stage in their careers. 

Ivanovic and Wozniacki will meet in the second semifinal at about 5:30 or 6:00 P. M. local time, or 7:30 P. M. Eastern Time, on Saturday.