20th Annual Arthur Ashe Kids' Day
Credit: Uri Schanker/FilmMagic

Now that is what we call power. The U.S. Open, which kicks off today, has sold out of tickets for the women's tennis final before the men's final, according to ESPN. Officials believe that this is the first time it has happened in the tournament's history. And in large part they have Serena Williams to thank—if she wins the Open, the 33-year-old athlete would achieve a single-season Grand Slam and be the first woman to do so since Steffi Graf did in 1988. The women's finals will most likely start Sept. 12.

Williams told Yahoo News, "I decided I prefer to have that pressure than the pressure of not winning. Not everyone can handle that pressure, but I'm OK with it. I would rather be in this position than another one."

The tennis pro will wear pieces from her new collaboration with Nike, called the Serena Greatness Collection for Nike, you can now shop the collection today on and in select Nike stores.

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