By Nick Georgandis Photo Credit: Natasha Peterson / Corleve and Andy Kentla

(September 10, 2011) The current world No. 1, the 13-time Grand Slam champion, a former French Open finalist and ... Angelique Kerber? If you had that quartet as your final four for the US Open when play began 12 days ago, drop whatever you're doing, get in your car, hit the nearest convenience store and immediately buy a Powerball ticket.
For the rest of us, here's a preview of Saturday's women's semifinal machups.
Samantha Stosur (AUS) vs. Angelique Kerber (GER) - The other matchup will get all the hype, but this one is just as intriguing a story, and definitely more surprising. Since reaching the 2010 French Open final and the No. 4 spot in the world, Stosur has been on a slow fade, including third-round losses at Australia and France this year, and a first-round defeat at Wimbledon. Entering the Rogers Cup, she was an unimpressive 23-16 on the year, but proceeded to win eight of 10 matches in reaching the Toronto finals and the Cincinnati quarters.
The Aussie has been an absolute warrior so far at Flushing Meadows, going the distance to edge Nadia Petrova 7-6(5), 6-7(5), 7-5 and Maria Kirilenko, 6-2, 6-7(15), 6-3.
Her opponent, the 23-year-old, 92nd-ranked Kerber, is in uncharted territory, with zero career WTA titles and a losing record (15-18) entering the Open. Since upsetting 12th-seeded Agnieszka Radwanska in the first round, Kerber has needed just nine sets to slice her way through four more opponents, including Flavia Pennetta - who had in turn upset both Maria Sharapova and Peng Shuai - in the quarterfinals.
Stosur and Kerber have never met on the court professionally. Kerber is the second German woman to make a Grand Slam semifinal this year, following Sabine Lisicki, who did so at Wimbledon.
Caroline Wozniacki (DEN) vs. Serena Williams (USA) - The No. 1 without a Grand Slam against the 13-time Grand Slam winner who has her sites set on once more obtaining that top spot.
Is there any question why this one is set for a primetime weekend audience?
Wozniacki and Williams haven't met since the end of the 2009 season and only twice ever, with Williams taking both matches. Wozniacki was upset by Vera Zvonareva in this round a year ago when she looked like a dead cinch for the finals.
She's only lost one set so far, that to Svetlana Kuznetsova in the fourth round. Her one and only Grand Slam final came here two years ago. Until she wins one, she's a paper champion, unlike Williams who has taken this tournament three times, WImbledon four times, the French Open once and Australia five times.
After losing her first set of the tournament, she's won 10 straight and looks just plain unstoppable, not surprising given she's now 21-2 in 2011.