On the verge of exacting revenge for a terrible loss at the French Open two years ago, Maria Sharapova stumbled, cursed, and found herself once again at the mercy of Dinara Safina.

Sharapova, who took over the no. 1 ranking when Justine Henin retired last month, led 7-6(6), 5-2 in yesterday’s fourth round match. At 5-3, she had match point on her serve. Safina erased it with a backhand winner, broke serve, and pushed the set to a tie-break, where Sharapova took a 5-2 lead before losing the next five points. After nearly three hours of play, and a rain delay of an hour and half, Safina celebrated a 6-7(6), 7-6(5), 6-2 victory and her second trip to the French Open quarterfinals. Sharapova walked off the court to a chorus of boos, a response to her shrieks, which increased in volume as the match progressed, and her colorful language (in English).

Safina’s first French Open quarterfinal came in 2006, also at the expense of Sharapova. The two met in the fourth round, and Sharapova won the first set 7-5, lost the second 6-2, and led 5-1 in the final set. She didn’t win another game (Safina won 18 of the last 21 points). Though Sharapova had a bigger lead that year, this loss was more of a disappointment. Sharapova is 21 years old now, and she won her third major title at the Australian Open in January. She’s taller, fitter, stronger, and more mentally prepared than ever before. This is a match she should have won, clay court or otherwise. That she didn’t says a lot about Sharapova and the women’s game in general.

Sharapova, like the rest of today’s top young women, seems to have front-runner phobia (this is the fourth time she has held the no. 1 ranking, which she may well lose again after this tournament). Just when she seems ready to join the ranks of the game’s past dominant champions — women like Margaret Smith Court, Billie Jean King, Chris Evert, Martina Navratilova, Steffi Graf, Monica Seles, Martina Hingis, and Venus and Serena Williams — she retreats. None of her colleagues seem capable of more. (Henin came close to fulfilling the role of leader the last few years, but she was too often injured or depleted by the end of tournaments.)

One could read this as a sign of greater depth in the women’s game, and that’s true up to a point: The 100th ranked player today is no doubt far better than the 100th ranked player of 20 years ago. But at the top of the rankings, I’d argue that there’s less depth than in years past; that there are fewer women who have the combination of physical skills and mental fortitude to be consistent champions. Today’s top women are also developing a bit later, which is natural considering the ever-increasing emphasis on size and power. The days of a champion like Hingis, who reached the final of all four majors, and won three of them, in 1997, when she was 16 years old, are gone. But will any of the current crop of young talents — Sharapova, Ana Ivanovic, Jelena Jankovic, and Svetlana Kuznetsova being the leading candidates — call the game her own for an extended stretch?

Sharapova, who has won the other three majors once each, has the competitive spirit and the ground strokes to win on any surface, but her sloppy footwork and serve — at times splendid, at times a double fault waiting to happen — make her vulnerable. Kuznetsova usually lacks patience and oftentimes confidence. Ivanovic has the most well-rounded game, but her long strokes rob her of time on fast surfaces, and jitters sometimes get the best of her serve. Jankovic is the quickest around the court and has a laser backhand, but she has no serve to speak of and a tendency to cast blame on the nearest object when she struggles (a chair umpire, her racquet, a noise from the crowd, or instant replay). They are a flawed bunch and, though often fun to watch, not reliably great, as many past champions were, or as the top three men in the game are today.

Perhaps many fans would prefer a world where next to each trophy is a different smiling face. But having a front-runner has benefits for fans and the tour alike. Look no further than the men’s tour. Roger Federer had Pete Sampras as an example, and he’s now on pace to break Sampras’s all-time record of 14 major titles. Federer’s dominance during the last few years has pushed Rafael Nadal and Novak Djokovic to work harder, practice more, and develop into champions, perhaps sooner than they might have otherwise. When someone is far ahead of the pack, the pack must work harder to catch up. That’s not happening in women’s tennis right now. No one inspires awe. No one inspires fear, at least not in the way Serena Williams once did. No one seems unbeatable. All upsets are mild upsets, unless they involve players outside the top 10 or 15 in the rankings. Safina just knocked off the top seed in one of the most important victories of her career, but does anyone doubt that the odds of her winning her next match, against Elena Dementieva, are 50-50?

Maybe this year’s French Open will put a quick end to a changing of the guard that, at the moment, seems like it might last for years. Ivanovic is the most determined, and steadily improving, player remaining. Is it her time, or if not, at least her tournament?

***

Ivanovic should win a major one day — then again, that’s what people used to say about Gael Monfils. The long-limbed, lightning-fast, and powerful Frenchman was the best junior in the world, but his pro career has been a study in stubbornness (he has tried to make his mark as a defensive player despite incredible offensive tools) and injuries. In Paris this year, Monfils is again showing the talent that had many calling him a future champion. The 21-year-old reached his first major quarterfinal yesterday with a victory over Ivan Ljubicic, 7-6(1), 4-6, 6-3, 6-2. He’ll next play David Ferrer, who defeated Radek Stepanek in five sets, 4-6, 6-2, 1-6, 6-3, 6-3.

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