Upsets and injuries were contagious on the professional tennis tour last week. Rafael Nadal, winner of 103 out of 104 clay court matches since April 2005, suffered a foot injury and lost his second-round match at the Rome Masters to Juan Carlos Ferrero. Justine Henin, the world no. 1 who has struggled to find a rhythm all season, failed in Berlin against Dinara Safina, who had never beaten Henin in her career (she was 0-5 beforehand). Serena Williams couldn’t solve Safina, either, and so went her hopes for a fourth consecutive title (she had lost one match all year). Ana Ivanovic, the defending champion in Berlin, was forced to play twice in a day because one of her matches was stopped owing to darkness. Her loss to Elena Dementieva in the semifinals means she will lose her no. 2 ranking today (it now belongs to Maria Sharapova). Roger Federer? He lost again, this time to Radek Stepanek.

Of these upsets, Henin’s is the most concerning. Henin hasn’t played like a no. 1 player this year. If anything, she’s barely played at the level of a top-20 player — she hasn’t defeated someone inside the top 25 since the third round at the Australian Open. In Australia, she won only four games against Sharapova; last month, she won just two against Serena Williams in Miami. Her one title came in Antwerp, where she didn’t play anyone ranked higher than no. 47. Henin remains no. 1 because of the strength of her last two seasons, in which she reached the final round in six out of the seven Grand Slam tournaments she played — and she won three of them.

Even when Henin begins a year slowly, she usually rounds into form by May. Clay is her best surface and while she never seems invincible on it, as Nadal does, she hasn’t been pressed very often in winning four of the last five French Open titles. Her prowess on clay makes her loss to Safina all the more difficult to understand. Her subsequent withdrawal from the Rome tournament this week, which she announced over the weekend, is baffling. Henin said she was fatigued — but she’s played only 19 matches this season. I have no knowledge of Henin’s true physical condition, but there’s no reason she shouldn’t recover from a midweek loss in time to play the last French Open warm-up event the following week. The women’s tour agrees, and has fined her $20,000 for the late withdrawal.

It’s one of the great surprises in the history of the women’s game that the small and fragile Henin became a dominant no. 1. Knee and shoulder injuries always nag her, and she missed considerable time in her career due to a debilitating virus. She also struggles to keep her nerves in check: Unlike most players who reach the very top of tennis, Henin is not supremely confident. A fragile body and a fragile mind are not the chief ingredients of a champion, yet Henin has learned — with the help of stubbornness and a coach, Carlos Rodriguez, who is an expert motivator — to overcome these shortcomings. She’s approaching her 26th birthday and still has time to play outstanding tennis, but not much time. Without playing in Rome, it would be a surprise if she composes herself and wins a fourth consecutive title at Roland Garros.

The same cannot be said for Nadal. Unless his foot injury is more severe than he has so far disclosed, the world no. 2 shouldn’t arrive in Paris with any less confidence than he’s had the last three years. Nadal used the occasion of his defeat as another chance to disparage the men’s tour for packing the already dense clay court season into one fewer week this year. Knowing Nadal, this will be the last time he offers any sustained attack on the executives who run men’s tennis. For a man of such superb concentration, there’s no room for this kind of negative energy. Look for Nadal to talk less and win more, provided his foot is in good health.

Federer’s loss wasn’t as worrisome as Henin’s, but surprising considering how well he had played in the last few weeks. After a close loss to Nadal in the Monte Carlo final, he seemed fit and fully recovered from the mononucleosis-induced slump that hampered the early part of his season. Stepanek is comfortable on clay, but he is by nature an attacking, fast-court player, much like Mardy Fish, who drubbed Federer in Indian Wells earlier this year. Federer doesn’t see many players like this for the simple reason that few of them exist these days, so perhaps that’s why he is having more trouble with them of late. A more compelling reason, though, is that the tour’s second-tier players see that Federer can lose from time to time, and that this old-fashioned method — what was once known as “the big game” — can produce wonderful results. Once in rhythm, Federer is nearly unbeatable. The few men who can serve-and-volley and shorten points prevent him from finding a groove and improve their chances. If there’s one benefit in losing for Federer, it’s that he won’t have to worry that this week’s tournament in Hamburg, where he is the defending champion, will sap his strength for the French Open.

With most of the big names exiled from Rome, Novak Djokovic cleaned up. The world no. 3 can’t expect to win a Masters event on clay this easily ever again. He didn’t have to play Federer. He didn’t have to play Nadal. Two opponents, Nicolas Almagro and Stepanek, retired against him with injuries. Stanislas Wawrinka, who plays in the very long shadow of his Swiss compatriot Federer, reached the final when Andy Roddick (yes, on clay!) retired in the semifinals with a bad back (Roddick will miss Hamburg because of the injury). Djokovic prevailed in the final 4-6, 6-3, 6-3. In Berlin, Safina finished off her fine run with a 3-6, 6-2, 6-2 victory over Dementieva.

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