This latest reinvention of Serena Williams has provided us a revelation of sorts:
The theory often has been advanced that the sport is merely a convenient vehicle for Serena's many extracurricular hobbies. But there were tears when she won her first match at Wimbledon over Aravane Rezai after nearly a year away from the game. The "come ons" as she wrecked Maria Sharapova at Stanford. A few rousing fist pumps in the general direction of Victoria Azarenka and Samantha Stosur on her way to the Rogers Cup title in Toronto.
But surely, the most telling sign that Serena desperately wants to succeed as age 30 rapidly descends?
She's putting in the hard miles -- literally.
"I hate running," Serena said recently. "I have been doing a little more running. More distance running.
"I just decided if I could be fit, maybe that can be a new level in my game. I've always been, I think, a halfway-decent player. I thought, 'What haven't I been?' I have never really been fit, you know.
"I'm still not superfit, because I always have cream sodas at night."
Cream sodas aside, this represents something of a breakthrough for Serena. Mardy Fish had a similar late-career epiphany a year ago, and it catapulted him into the top 10, but he has yet to win a major. What happens when a 13-time Grand Slam singles champion decides to take training seriously?
She becomes the favorite to win the U.S. Open with just four-plus tournaments under her diminishing belt after a series of major health scares.
Jim Courier, who played a senior exhibition match at the Toronto event, has been watching Williams closely.
"I don't know why it feels this way," he said, laughing, "but I feel like she's a bigger favorite to win than Novak [Djokovic.]."
Which is saying something.
"I look at [Petra] Kvitova and [Li] Na, and I see them trying to deal with newfound celebrity and the pressure that comes with it. I wonder if they can produce their best tennis at the U.S. Open.
"I don't see anyone in the draw that can push Serena the way she's playing. There are more guys in the men's draw that can potentially push Novak, who actually believe they can win."
We have seen this from Serena before.
She never has chalked up perfect attendance at the majors; she missed one event every year from 2002 to 2005, then skipped two in 2006. After battling a knee injury that forced her to miss Roland Garros and Wimbledon, she finished 2006 as the WTA's No. 95-ranked player.
Naturally, Serena came back to win the Australian Open in January 2007, spanking Sharapova 6-1, 6-2 in the final. Nearly five years later, she's poised to do it again.
Serena was on top of the game after winning Wimbledon a year ago, but a well-documented run of bad luck -- lacerations on both feet, two surgeries, a clot in her lung and surgery to remove a dangerous hematoma -- forced her to miss a career-high three consecutive majors.
Serena suddenly reappeared at a Wimbledon warm-up tournament intent on defending her two consecutive Wimbledon titles. She didn't win either event, but her back-to-back wins in Stanford and Cincinnati were reminiscent of Kim Clijsters' dramatic comeback two years ago. After a two-and-a-half-year retirement, Clijsters played in just two events, Toronto and Cincinnati, and won the U.S. Open.
With the Belgian officially out of this year's Open with a pulled adductor muscle, Serena has been the best among WTA players this summer. When she pulled out of Cincinnati last week with an aggravated right toe injury -- there was speculation that she really just wanted to attend Kim Kardashian's wedding --- she had fashioned a 12-0 record on North American hard courts. No one else is even close.
Serena's serve -- and a strong dose of fitness -- have helped raise her ranking from No. 169 to No. 80 to being a seeded player in New York. Now, will she have enough stamina to cross the finish line?
In Canada, Serena was asked whether she felt a kinship to Roger Federer, who has beaten her to age 30 by a few months.
"No," she said. "Baby, I'm 26. I'm turning 27 this year."
Greg Garber is a senior writer for ESPN.com.
