2009 U.S. Open champion Kim Clijsters
Photo: AP/Charles Krupa
On September 14, 2009, Belgian women's tennis player Kim Clijsters extended her U.S. Open winning streak to 14 consecutive matches—and won the second straight U.S. Open tournament she's played in. This would be a classic example of a player dominating her competition, except for an odd twist—Kim Clijsters' back-to-back titles come four years apart.

In late 2005 and through much of 2006, 22-year-old Clijsters was at the top of her game. She won the 2005 U.S. Open, advanced to the semifinals at the 2006 Australian open and regained her position as the world's top-rated women's tennis player (she had earned the number one ranking in 2003). But in the summer of 2006, her fortune turned.

At a tournament in Montreal, Clijsters slipped and injured her wrist, forcing her to take a couple of months off and miss her chance to defend her U.S. Open title. Although she came back later that year, Clijsters was not up to her previous level. She posted a note on her personal website in May 2007 announcing her immediate retirement. Though she was then not yet 24, injuries left her unable to continue competing. Clijsters' career arc seemed all too common in women's tennis—a bright star with amazing early success whose career abruptly ends because of bad luck and injuries. The sports world was left to wonder: What if?

During her 27-month retirement, Clijsters' personal life was full of drama, both good and bad. In 2007, she married Brian Lynch, an American basketball player who plays in Belgium. In 2008, she gave birth to their daughter, Jada. In 2009, her father, a professional soccer player, died of lung cancer.

In March 2009, Clijsters announced she would dip a toe in the water, testing her enthusiasm for a full-scale comeback with wild card entries into three tournaments: warm-up tournaments in Cincinnati and Toronto and a return to the scene of her greatest success, the U.S. Open at the National Tennis Center New York City. As a wild card, Clijsters was able to enter these tournaments despite not having a high ranking—which she lost by retiring—and not having to play her way in as a qualifier.

"What if?" would finally be answered.