Is Pennetta's win the start of an unraveling WTA Tour?

— -- NEW YORK -- The final weekend of the latest US Open promised to be a historic one, and so it was -- albeit not in the way almost everyone expected. Instead of Serena Williams becoming just the fourth woman to complete a calendar-year Grand Slam, tennis had its first all-Italian Grand Slam final.

You might have dreamed up any number of alternate scenarios for how this US Open would end: Victoria Azarenka avenging herself on Serena for beating her in all those recent three-setters. Madison Keys emerging as the successor to the Williams sisters by serving her way to the title. How about Bethanie Mattek-Sands winning the singles title with her head shaved and then and break-dancing during the trophy presentation ceremony? Only that last one might have strained credulity to the extent that reality did.

Instead, the unlikely tournament winner promptly announced her retirement -- sort of anyway. Flavia Pennetta, who overcame some early jitters to overwhelm her childhood friend Roberta Vinci 7-6 (4), 6-2 to win the US Open, waited until the very end of the presentation ceremony to add, almost as an afterthought, "This is the way I want to say goodbye to tennis."


The decision was surprising but not exactly shocking, given that Pennetta is 33 years old and ranked 26. She later clarified her statement, saying she won't defend her US Open title in 2016, but might play certain events for the rest of this year, including the year-end WTA Championships (if she qualifies).

The final seemed emblematic of this edition of the US Open, which produced a bumper crop of impact players (led by Vinci herself, a semifinal winner over Serena Williams) as well the greatest number of three-set women's matches here, ever.

It all began with one theme holding the draw together like a steel cable, Serena striving to become the first woman since Steffi Graf in 1988 to accomplish that single-year Grand Slam. But by the final Saturday, as a spitting rain began to fall on Arthur Ashe stadium through the giant hole awaiting a roof, the tournament seemed like a tangled ball of unconnected bits of string.

Maybe that's a good thing, maybe not. In either event it points to the biggest question facing the WTA Tour as Serena Williams approaches her 34th birthday later this month: What happens when she's gone?

The draw provided no clear answer, because she wasn't beaten by a rival, or by one of the women seen as a potential successor. The most dangerous women she might have faced at this tournament not only failed to stop Williams, but they didn't even show up to match wits and shots with her.

Sloane Stephens? The No. 29 seed lost in the first round to CoCo Vandeweghe. Number 12 Belinda Bencic, who had taken Serena's measure a few weeks earlier in Toronto? She was beaten in the third round by Serena's 34-year-old sister, No. 23 Venus. Last year's sensation No. 25 Eugenie Bouchard? Out before the quarterfinals with a concussion after an accidental fall in the locker room. Credit Keys and Venus for showing up to meet -- and lose to -- Serena.

So much for that overloaded quarter of the draw over which Serena found herself presiding.

In the lower half of the draw, Serena's potential final opponents were thought to be either No. 2 Simona Halep, No. 5 seed Petra Kvitova, or, perhaps most likely, No. 20 Azarenka. But all of them stumbled out.

Granted, not every woman seen as a threat to Serena would have had a chance to play her. Some would have eliminated each other. But the bigger point is that there is no reliable pecking order; the WTA Tour is in a state of flux -- chaos, if you prefer.

Adding to this sense of the unknown: Maria Sharapova, who's been fairly reliable as a distant No. 2 to Serena, is injured again. She hasn't played since Wimbledon, and there's no sign she'll be back anytime soon.

There are other strong signs that the tour is in midst of a sweeping transition. There have been 44 tournaments played thus far this year. They've produced 27 different winners, but only nine women who won two or more events (and that includes players as far under the radar in the name recognition department as Timea Bacsinszky, Anna Karolina Schmiedlova and Teliana Pereira).

Among those who haven't won a tournament yet this year are known players including: Ana Ivanovic, Agnieszka Radwanska, Victoria Azarenka and Jelena Jankovic.

From here, the tour moves to Asia for a long, fall unwinding. "Unraveling" might be a more appropriate word, unless Serena Williams decides to show up once again to restore some semblance of order. I wouldn't hold my breath, though. She can do it only so many times. And after Serena, the deluge.