Friends don't let friends beat them in the final

Serena Williams and Caroline Wozniacki are close friends. Tomorrow, they will face off against each other for the 2014 U.S. Open singles title, and each of them has a compelling backstory.

Williams, of course, is looking for her 18th major title. Most observers thought she would have already grabbed it by now, but until she arrived in New York, Williams was unable to get past the round of 16 in a major this year. She was taken out of the Australian Open, the French Open and Wimbledon by Ana Ivanovic, Garbine Muguruza and Alize Cornet, respectively. But at the U.S. Open, she has looked more like the Serena Williams who is destined to be the last woman standing.

Williams has won the title five times, starting in 1999. Wozniacki, on the other hand, has never won it, though she was a finalist in 2009, when she lost to Kim Clijsters. A fast-moving athlete with impressive endurance, Wozniacki used her crack defensive game to take her all the way to the number 1 ranking several years ago. Her critics continually pointed out her lack of aggression as her only real weakness. Coaches came and went, sometimes quickly, and Wozniacki always returned to her father Victor (formerly known as Piotr) as her coach.

Eventually, the Dane slipped down in the rankings, and faced with a new appreciation of aggression on the tour, found it harder to win matches than it had been before. She also experienced a very public, flashy romantic relationship, and then a very public breakup. She found solace in spending time with her friend, Serena. And then, from the many and varied elements of her history emerged a new tennis player--a fast, enduring, defensively gifted player who hits winners and takes charge of rallies.

It is this newer version of Wozniacki who will compete against Williams for the title on Sunday. Here are their paths to the final:

Serena Williams

round 1--Taylor Townsend
round 2--Vania King
round 3--Varvara Lepchenko
round of 16--Kaia Kanepi
quarterfinals--Flavia Pennetta (11)
semifinas--Ekaterina Makarova (17)

Caroline Wozniacki

round 1--Magdalena Rybarikova
round 2--Aliaksandra Sasnovich
round 3--Andrea Petkovic (18)
round of 16--Maria Sharapova (5)
quarterfinals--Sara Errani (13)
semifinals--Peng Shuai