Somewhere in Belgium, or on a tropical island, or deep inside a rain forest, wherever Justine Henin is these days, the former world no. 1 should be asking herself: “What was I thinking?”

The four-time French Open champion is not the sort to have misgivings. When Lindsay Davenport left the tour to have a baby, the odds were good that she would return. Kim Clijsters, now married with a child, likely hasn’t seen her last Grand Slam tournament (give her a little time). But when Henin announced her retirement last month, most of the tennis world concluded that she would never return. I doubt she will, yet considering events at this year’s French Open, even a person as resolute as Henin might need an inordinate amount of liquor to keep from wondering whether she had made a rash decision. The way this tournament has unfolded so far, Henin could have won the title for a fourth straight year with little motivation and little practice — and little sleep and little to eat. In Paris, the women’s title might just as well go to one of the top four seeds, who are alive and well, a journeywoman like Patty Schnyder, or a qualifier on a surprising run to the quarterfinals. It’s anyone’s guess.

The favorite, now that Serena Williams is gone, appears to be Ana Ivanovic, last year’s finalist. The 20-year-old Serb didn’t lose a game in her fourth-round match yesterday against qualifier Petra Cetkovska and hasn’t lost a set so far. She also hasn’t played a quality opponent. Her first test will come in the quarterfinals against Schnyder, the steady, moon-ball-loving lefty who yesterday did so easily what Serena Williams could not do: defeat doubles expert Katarina Srebotnik.

If there’s any doubt about Ivanovic, it’s that she’s never won a major title before. Even so, she’s one of the more experienced women remaining in the draw. Of the 12 women left, only two — Maria Sharapova and Svetlana Kuznetsova — have won major titles. Neither of them has won the French Open. Ivanovic has reached two major finals in the last year and has a game with no glaring weaknesses (there are no overwhelming strengths, either, but players with far less have won major titles in the past). She’ll also benefit from the fact that her likely semifinal opponent, Jelena Jankovic, is hurting. Jankovic scored a 6-3, 7-6(3) victory over Agnieszka Radwanska yesterday while twice receiving treatment on her right shoulder and neck. Her right arm remains wrapped in tape.

If Jankovic wins this tournament, she will take over the top ranking. But don’t be surprised if Carla Suarez Navarro, a 19-year-old qualifier from Spain, upsets the no. 3 seed and earns a spot in the semifinals. Navarro had never played a match at a Grand Slam tournament before this event, but she’s moving through the draw like a veteran. She defeated former world no. 1 Amelie Mauresmo in the second round and pummeled Flavia Pennetta (the woman who defeated Venus Williams) 6-3, 6-2. Navarro is the first qualifier since 2001 to reach the quarterfinals at the French Open.

Russians have seized control of the other half of the women’s draw: Five of the eight women remaining are Russian, and another, the impressive Victoria Azarenka, is from Belarus (Azarenka has lost six games total in her first three matches). Sharapova continues to double-fault (36 in three matches) and slide awkwardly on the clay, but she’ll play Dinara Safina today for a spot in the quarterfinals. (Safina handed Sharapova one of the worst losses of her career in the 2006 French Open when she recovered from a 5-1 deficit in the final set.)

If one were to go by form, style, and skill, Kuznetsova, the no. 4 seed, would be the favorite to reach the final and perhaps win the tournament. Kuznetsova has spent much of her life training on clay in Spain. She runs as well as anyone on tour, hits powerful ground strokes, volleys well (she plays a lot of doubles), and serves well, too. Since winning the U.S. Open in 2004, Kuznetsova has remained near the top of the rankings and reached two other major finals. Both times, in Paris in 2006 and at the U.S. Open last year, Kuznetsova lost to Henin. Kuznetsova and Henin spoke before this tournament began, and Henin said that this might be the Russian’s year. If it is, Henin ought to get a share of Kuznetsova’s earnings.

In the Open Era, women’s tennis has been more predictable than men’s tennis. These days, the opposite is true. As the second week of the French Open begins, the top three seeds in the men’s draw — Roger Federer, Rafael Nadal (the three-time defending champion), and Novak Djokovic — not only look like certain semifinalists; it’s as if the tournament doesn’t begin until then. There have been a few surprises, though, the biggest being Nikolay Davydenko’s loss to Ivan Ljubicic after winning the first two sets. Davydenko’s loss makes Federer’s relatively easy road to a third straight final that much easier.

Can anyone stop the march of the big three? If Robby Ginepri, the once struggling American, wins today, he’ll try his hand against Federer in the quarterfinals. The match would pose a problem for Jose Higueras, who coaches both Ginepri and Federer (Higueras might have to watch on television, rather than choose a player’s box to sit in). Djokovic also shares a mentor with the man he’ll meet in the quarterfinals, Ernests Gulbis, a 19-year-old from Latvia who hits the ball as hard, and returns serve as aggressively, as anyone in the game. Both Djokovic and Gulbis trained at Niki Pilic’s tennis academy in Germany.

Djokovic will be the heavy favorite, and if he wins, his prize will be a chance at Nadal in the semifinals. Yesterday, Nadal defeated fellow Spaniard Fernando Verdasco 6-1, 6-0, 6-2. He’s lost only 22 games in four matches despite struggling with blisters on his feet and, for a spell yesterday, dizziness. His next opponent, Nicolas Almagro, hits the ball too hard and serves too well (78 aces so far, most in the tournament) to be called a typical clay-court Spaniard. The two have met twice before on clay, and Nadal won both times in straight sets. As formidable as Federer and Djokovic are, Nadal seems on course to beat them both, and he just might do it without losing a set. We’ll have to wait until Friday, when the real men’s tournament begins, to find out.

Mr. Perrotta is a senior editor a Tennis magazine. He can be reached at tperrotta@tennismagazine.com.