MIAMI — Serena Williams races through the first 10 games, losing one. She hits clean winners, both forehands and backhands. She serves four aces. Jelena Jankovic misses and misses again. And again. Then Williams misses once, twice, three times. More times. It’s one set apiece. Suddenly, Jankovic is finished as Williams serves at 5–0 in the third set. Williams is nervous? Nervous? Yes, nervous. She has won this title four times and major titles eight times, and she can’t hit the ball over the net on match point. She lets seven match points slip away and Jankovic laughs at her luck. Finally, after a busted racket and a few screams, Williams mercifully ends it.

Saturday’s final at the Sony Ericsson Open in Miami between Williams and Jankovic was a strange, up-and-down affair, and it’s tempting to write off its odd plot as an anomaly, a rare case when Williams had the shakes and couldn’t put away a dogged defender. But perhaps this final was not just a strange match, but a lesson on where Williams stands these days. The last truly dominant champion in women’s tennis is fitter than she has been in years and seems to be working harder than she has in years, too. She says she has put tennis first — “my whole life is dedicated to nothing but tennis,” she said — yet she’s clearly not the assured, confident champion she once was. Williams of 2002 wouldn’t have fumbled her way through seven match points. She wouldn’t have blown a 6–1, 3–0 lead. She wouldn’t have blinked.

Is it possible for any formerly dominant champ, even one as superior as Williams, to recapture the aura of invincibility once it’s lost? History suggests not, no matter how talented and dedicated the champion. New players arrive with new shots and fresh legs and little concern for what you used to be. Like all aging tennis greats — she’ll celebrate her 27th birthday later this year — Williams seems to think more on the court these days. She seems more aware that her career will end in six or seven years at most, and that her best days may be gone in three years. Important matches, such as this weekend’s final, do not come along every week, but every few months (or perhaps less often than that — after winning this title last year, Williams didn’t win another until a month ago in Bangalore, India). When one has fewer chances to win titles, it can become more difficult to execute when the time comes along. Williams admitted that the tension got the better of her against Jankovic.

“I did get tight, you know,” she said. “I think everyone gets tight at some point. But the fact that I did today, I feel that it definitely — you can definitely see my desire and my dedication.”

Most fans have longed for Williams to rededicate herself to tennis and she has received a lot of criticism over the years for not pushing herself to her limits. It’s not unfair to ask more of her (or, for that matter, anyone), but it is unfair to suggest that her failure to give more is somehow disrespectful to the sport. Most of us don’t give our all every moment (frankly, no one does). If someone can win eight major titles, start a successful fashion company, and dabble in acting — and not commit herself 100% to any of those things — why shouldn’t she? It’s her choice and she’s earned the right to make that choice as much as the rest of us have the right to ask for more.

If Williams has indeed decided to put tennis first — and one look at her physique suggests that she has — it’s admirable for her to admit to it. It’s akin to admitting that for her, tennis is more difficult than it used to be. She says she is doing more, yet winning is more of a struggle. She’s trying to find that dominant champion, but she can’t quite do it. She still fights on the court as well as ever and she’s not unlikely to steamroll a top player, as she did to Justine Henin this week. She just as likely might struggle against lesser opponents (at this tournament, that opponent was Italy’s Flavia Pennetta). For the first time in Williams’s career, winning titles takes a lot of work, and perhaps a little luck, and she seems to have embraced that new reality.

“I’ve been working so hard, and I feel like everything will come together in time,” she said. “Sometimes when it doesn’t come together I get frustrated, but I feel like it’s not going to be in vain.”

Williams had a touch of uncertainty in her voice when she delivered those lines. She also sounded a bit unsure when she said she was “bound to” become comfortable again at Wimbledon and the U.S. Open, where she suffered two difficult loses to Henin last year. Maybe she will, maybe she won’t. But if Williams looks hard enough for that old champion she used to be, it won’t be long before she finds a new one — one who might not dominate every match — win every tournament, or strike fear in the hearts of her opponents. She’ll win sometimes and remain wonderful to watch. It suits her, and tennis, just fine.

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It’s not often when Andy Roddick beats Roger Federer (he’s now 2–15 against the world no. 1), but who would have guessed that Roddick and his upset in Miami would play second fiddle to Nikolay Davydenko? The world no. 4 played two of the best matches of his career at this tournament, beating Roddick in the semifinals and Rafael Nadal in the final, 6–4, 6–2. The reason for his success? A new racket. Davydenko has only one model of his new Prince (as he put it, “I have two racquets, but second racquet is not so great”). He used it the entire tournament, replacing strings between matches and hoping they didn’t break during play.

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