Flavia Pennetta beats Simona Halep in U.S. Open semi to reach her first Grand Slam final at age 33

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This victory ties Serena Williams with fellow U.S. tennis legends Chris Evert and Martina Navratilova at 18 Grand Slams. If Serena wins on Saturday, she will hold the record for most U.S. Open titles in the Open Era with seven.

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Serena Williams' first time back in the U.S. Open final since 2002. She defeats Jelena Jankovic in straight sets to cap the triumphant return.

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Serena Williams flashes a pair of 2s after beating Angelique Kerber in the 2016 Wimbledon final to capture her record-tying 22nd Grand Slam title. Serena has now equaled the modern-era majors record held by Steffi Graf.

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Flavia Pennetta celebrates her upset victory in the U.S. Open semfinals on Friday.

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Now let's take a look back and how Serena got to 22: She captures her first major title with a straight-sets victory over Martina Hingis. Serena becomes the first African American woman to win a Grand Slam event in the Open Era.

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The first of many times Serena Williams defeats her sister Venus in a Grand Slam final. She successfully prevails here in straight sets.

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Serena Williams' first of six Aussie Open titles completes the "Serena Slam" as she holds all four major titles at the same time. This time it takes three sets to beat her big sister Venus.

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Just like in 2012, Serena Williams beats Victoria Azarenka in three sets, this time with a tiebreaker in the second set, to reign supreme in Queens.

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After breezing by defending champion Petra Kvitova in the quarterfinals, Serena Williams beats Agnieszka Radwanska to win her third Wimbledon in four years.

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It was Serena's seventh win in nine all-Williams Grand Slam finals, and the first since Wimbledon in 2009. It was 36-year-old, No. 13-seeded Venus Williams' first trip back to a major final in 7 1/2 years.

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Serena Williams beats Maria Sharapova for the 16th straight time to win yet another Australian Open. Williams has never lost at Melbourne Park when she makes the finals.

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Flavia Pennetta (l.) beats Simona Halep in straight sets to advance to her first Grand Slam final.

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Serena Williams ends the longest drought at any Grand Slam in her career with a win over Maria Sharapova to finish atop the French Open for the first time in 11 years.

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Serena Williams won her record 23rd Grand Slam singles title with a 6-4, 6-4 victory over her older sister Venus in the Australian Open final. With her record seventh Australian title, the 35-year-old Williams moved ahead of Steffi Graf for the most major titles in the Open era. Margaret Court won 24 majors, but collected 13 of those before the Open era.

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After a shaky first set, Serena Williams comes back to beat Lindsay Davenport, who is still the only other American she has faced in a major final besides her sister Venus.

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Lucie Safarova pushed Serena Williams to the limit, but the American came out on top in three sets to win and mark her third Career Grand Slam.

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Serena Williams wins the title at Wimbledon for the first time in six years after finishing as the runner-up to Venus in 2008 and Maria Sharapova in 2004. This is the last time the Williams sisters have faced off in a major final.

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It takes less than an hour for Serena Williams to beat Dinara Safina and join Steffi Graf as the only women to win four titles in the land down under.

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Serena Williams becomes the oldest woman to win a major in the Open Era with a straight-sets victory over Garbine Muguruza.

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For the fifth time in two years, Serena Williams defeats her sister in a Grand Slam final.

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For the first time in four years Serena Williams wins the U.S. Open, making up for her straight-set loss to Samantha Stosur in the finals a year earlier

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Serena Williams does not drop a single set, including in the final against Vera Zvonareva, en route to her fourth Wimbledon crown.

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Serena Williams avenges her 2001 loss to Venus at Arthur Ashe Stadium in Queens with another straight-set win.

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Justine Henin gives it her all but it is not enough as Serena Williams wins to tie the legendary Billie Jean King with 12 career majors.

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For the fifth time in two years, Serena Williams defeats her sister in a Grand Slam final.

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Serena Williams is all smiles as she gets her hands on a 7th Wimbledon trophy.

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The third installment of the battle between the Williams sisters. Serena makes quick work of Venus, who is going for her third straight Wimbledon title, to improve her career Grand Slam final record against her sister to 2-1