VICTORIA DUVAL: A delightful Haitian-American 17-year-old with a big, and growing, game, Duval shocked everyone when she defeated the 2011 US Open champion Sam Stosur in the opening round. "Vicky," playing in just her second US Open, made waves with her performance, personality and intriguing family back story -- enough to land her a guest spot on "The Tonight Show" during the second week of the Open.
RICHARD GASQUET: One of the most naturally talented shotmakers on tour, the Frenchman shook off a history of collapses in early rounds and late sets to emerge the stronger player, and victor, in two consecutive five-set battles, including one over the warrior David Ferrer in the quarters. A newly fit Gasquet displayed heart and fight in reaching his second career Grand Slam semifinal, a full six years after his first at Wimbledon.
ALISON RISKE: Unseeded and toting a childhood memento, a frayed fragment of a security blanket, for good luck, the 23-year-old from Pittsburgh shocked former Wimbledon champion Petra Kvitova in the third round. The wild card affectionately known as Ally then strode into Arthur Ashe Stadium and gave Daniela Hantuchova, the eventual quarterfinalist, everything she could handle. Riske's bubbly personality and budding game won lots of admirers around the grounds. As no doubt did these comments after her loss: "I loved, gosh, absolutely everything. I think getting a match on Ashe under my belt was huge. I won't forget when I was playing the match, during a tribute to our soldiers, I'm sitting on the bench crying. I'm supposed to be playing and be serious right now, but I'm like crying because they're congratulating our awesome soldiers. I just think America is a pretty awesome place."
FLAVIA PENNETTA: It's tough to get labeled a breakthrough player at age 31, but when you've been through the wringer -- injuries compounded by personal and professional setbacks -- and come storming back, it's a beautiful thing. And it couldn't happen to a nicer woman. The resurgent Italian came into the Open with a ranking of 83 and promptly riddled off a series of upsets -- without losing a set -- over high seeds and hot players, including Top 10 countrywomen Sara Errani and Roberta Vinci, former US Open champ Svetlana Kuznetsova and streaking Simona Halep, everyone's pre-tournament darkhorse to go deep at the Open. Behold the new darkhorse.
TOMMY ROBREDO: The 31-year-old Spanish baseliner is another veteran on the mend, climbing injury mountain back up to a Top 20 seed. Though he carried a 0-10 career head-to-head into his fourth-round match with five-time champion Roger Federer, Robredo played stellar, confident and clear-headed tennis to pull off the upset and derail an anticipated quarterfinal between Federer and Rafael Nadal.
CAMILIA GIORGI: Small in stature and outfitted by her mom like a graceful figure skater, "Giorgi girl" nonetheless bounded onto the sport's biggest stage and throttled the former world No. 1 Caroline Wozniacki. The qualifier, ranked No. 136 coming in, played with aggression and surprising power, following a simple strategy: "When the ball comes, just hit it in the corners."
STANISLAS WAWRINKA: If Roger Federer is the Swiss who's sputtering, Wawrinka is the one who's clicking. The ninth seed reached his first career Slam semifinal with a flawless upset of Wimbledon and reigning US Open champ Andy Murray, a chaser for his round-of-16 takedown of fifth seed Tomas Berdych. Wawrinka attributes his breakthrough to newfound maturity gained from becoming a dad.
DANIEL EVANS: Virtually unknown on this side of the pond, the 23-year-old British qualifier Evans (ranked No. 179) parlayed a practice session with Roger Federer into a surprising run as a giant killer. Evans beat 11th seed Kei Nishikori out of the gate in straight sets, then followed it up with a five-setter over tall and talented Bernard Tomic. Evans even gave Tommy Robredo, who in the next round would vanquish Roger Federer, a good run before bowing out in the third round.