Party Like It's...2009?

There must be something in the air in New York this fortnight.

While we've clearly been treated to more than our fair share of breakthrough stories at the U.S. Open, as we stand on the verge of the Major's quarterfinal rounds you can't help but notice the names of a few veterans -- long counted out of contention at the Slams -- surviving into Week Two. And though many of the top seeds can still claim to be favorites for the titles here, the performances of these underdogs could bode well even after the grounds at Flushing Meadows go dark.

The men's draw has stayed a little more intact than it did at Wimbledon, but it wasn't entirely devoid of early upsets. Juan Martin Del Potro, champion here in 2009, bowed out in the second round and opened the door for another former champ to continue. Lleyton Hewitt, my choice for Cinderella in this quarter, took the edge in the pair's head-to-head by fighting back from a two-set-to-one deficit in their second round battle. A win over rising star Evgeny Donskoy a match later brought him entrée to his first U.S. Open fourth round since 2006.

He's now on court with fellow comeback kid adult Mikhail Youzhny who's seeded here, but far from playing at his best. The Russian, a semifinalist in New York back in 2010, has faced three tough players already and pulled off surprisingly one-sided victories in all of them. He has just a 1-5 record against Hewitt, though, so history is not on his side. But with both players looking to make their best Slam showing in quite some time, don't expect either to give up easily.

While Del Potro's early loss was the biggest on-paper upset in the men's bracket, the more shocking result came in yesterday's fourth round action. Five-time champion Roger Federer was taken to task by Spanish veteran Tommy Robredo, marking the first year since 2002 in which he didn't reach a Slam final. Robredo's win meanwhile put him back in rarefied territory -- the world #22, whose ranking peaked in the top five back in 2006, has now reached his first U.S. Open quarterfinal and made the final eight of two Majors this year. The thirty-one year old has never gotten further at any big event in his career, and set to meet 2010 champion Rafael Nadal next, I doubt he'll change that this time around. But by showing life just when his career seemed over might prove how much fight Robredo's got left in him.

Ana Ivanovic has been climbing her way back into the sport's elite for a few years, but the former world #1 has only made one Slam quarterfinal since winning the 2008 French Open. She looked poised to break that streak this week though, having dropped just five games against her first two opponents in New York, and taking the opening set from last year's runner-up Victoria Azarenka in their fourth round today. She didn't seem willing to cede the advantage either -- in a third set which "boasted" seven breaks in ten games, the Serb wouldn't allow Vika to serve out the match. She did eventually end her run at the Open, of course, but might have given herself some much needed confidence to finish out the year. Tite-less now since Bali, 2011, she might just be ready to recapture the glory that once brought her to the top of this sport.

It's been a little longer since Daniela Hantuchova was playing at her best. The one-time world #4 missed a big chunk of last season with an ankle injury and took her time to rebuild -- though she's put up wins over top ten players like Sara Errani in Brisbane and Petra Kvitova in Madrid, and even added a title to her trophy case in Birmingham, she nevertheless hasn't won a match at a Major since the 2012 Australian Open. That changed this week, though -- now ranked just inside the top fifty, the thirty year old was able to capitalize on a draw that had been cleared out by her opponents. 2011 champ Sam Stosur was dismissed in the first round and upstart American Alison Riske took out former Wimbledon titleist Petra Kvitova in the third. By beating both these Cinderellas, Hantuchova sneaked her way into her first U.S. Open quarterfinal since 2002 and sets up a meeting with Azarenka, a woman with whom she holds a super-tight 2-2 record. It'll be her first real challenge of the tournament, by far, but if she can take advantage of holes in her opponent's game, she might just get it done.

But by far the biggest comeback of this event has been long-unheralded Flavia Pennetta. The Italian was the first woman from her country to break into the top ten, doing so just before the 2009 U.S. Open and was my pick to make the semis at Roland Garros the year after. But with her compatriots stealing the spotlight in recent years and a series of injuries kept her off the court for much of 2012, she had not only fallen out of the top hundred, but way off the radar of even the biggest tennis fans. She'd had some strong results this year, though, reaching the final in Strasbourg and the fourth round of Wimbledon -- thanks mostly to the withdrawal of Azarenka in the second round -- but has really made her strides in New York. She delivered a one-sided loss to last year's semifinalist Sara Errani and followed it up with wins over 2004 champ Svetlana Kuznetsova and red-hot Simona Halep. Now in her fourth quarterfinal in Flushing Meadows, the clay court specialist has established this as her Slam of choice, and if she can pull off a win over fellow Italian Roberta Vinci in her next round, she would put herself security back on the map for the sport's elite.

It's been quite a while since these players have been at the top of their game, but they've all seemed to find a time machine to bring them back to better days. It's a long shot for any of them to walk away with the title -- in fact, only one of those still alive has even played in a Major final before. But if they can keep the clocks turned back just a little while longer, there's no telling what even bigger wins they can pull off as we close out this fortnight.