Melanie Oudin reached the quarterfinals of the US Open in singles in 2009 and won the mixed doubles there in 2011 with Jack Sock. (Getty Images)

As an unseeded 17-year-old, Melanie Oudin shook up the tennis world with a run to the US Open quarterfinals.

Now at the age of 25, after numerous health setbacks, the American has announced her retirement.

There is something I wanted to share with you all. I started playing tennis when I was seven years old, and I knew at nine that I wanted to be a professional tennis player. Not knowing at all how much work and dedication that would entail, I wanted it and gave it my all to reach that goal. My dream was always to play professional tennis at places like the US Open with the best in the world. I have been lucky enough to live my dream for the last nine years since I turned pro in 2008. Unfortunately, since the end of 2012, I have been struck with numerous health issues and injuries. I would work so hard to come back after being out, and then something else would happen. It has definitely taken a toll on me mentally and physically over the last five years or so. Competing with the best in the world requires your absolute best and without being 100% mentally and physically it is very difficult. After much thought, I have decided to make the difficult decision to retire from professional tennis. Tennis has given me so much and I will always be grateful. It wasn't exactly the entire career I had dreamed of, but in life things don't always go as planned. The people as in my friends and family, coaches, fitness trainers, physios, sponsors, and my agent who I have worked with over the years, I will always be thankful and appreciate you so much. I will definitely miss competing but I will not forget the many wonderful moments my tennis career has given me. I am very proud of how I always competed with lots of heart throughout my whole career. Lots of amazing memories to take away from it that I will never forget like being on the USA Fed Cup team, making final eight at the US Open, winning a grand slam in mixed doubles, and winning a WTA tournament on grass. I fell in love with the game of tennis when I was seven years old and it will always have a special place in my heart. I am sad to leave the sport I know and love, but I am very optimistic about what the future holds for me. Lastly, I want to say thank you to my fans that have followed me throughout my career and have stuck by me through it all. I am so appreciative for the support over the years. BELIEVE

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Here’s a look back at some of the career highlights of a player who made everyone watching her “BELIEVE,” famously etched on her sneakers as she made her historic run in 2009 at the year’s final major.

• Oudin’s first taste of Grand Slam success actually came at Wimbledon in 2009. As a qualifier, she reached the round of 16, defeating world No. 6 Jelena Jankovic along the way.

• It was at the US Open in 2009 that Oudin really became a household name. Granted a wild card for the tournament, she defeated four Russian players in a row: Anastasia Pavlyuchenkova, Elena Dementieva, Maria Sharapova and Nadia Petrova.

Her run ended at the hands of Caroline Wozniacki, but after the tournament, she cracked the top 50 in the world.

• In 2010, Oudin reached her first career semifinal at the Open GDF Suez in Paris, but wasn’t able to replicate her Grand Slam success, falling in the second round at Wimbledon and the US Open.

She did mark herself as a Fed Cup standout, though, helping to lead the U.S. to the finals against Italy and winning a match in the championship against Francesca Schiavone.

• While Oudin’s singles suffered the following year, she accomplished the biggest feat of her career in mixed doubles at the US Open, where she and fellow American Jack Sock won the tournament over Gisela Dulko and Eduardo Schwank in the final.

• Her singles game rebounded in 2012 as she captured her first career WTA title, winning the Aegon Classic in Birmingham on grass. Oudin’s final-round opponent? None other than Jankovic, whom she defeated on Wimbledon’s grass courts back in 2009. Oudin also picked up three ITF titles that season: one on clay and two on hard courts.

• Over the next few years, injuries and a heart condition severely hampered her efforts to stay on the court. In 2016, she reached her first ITF singles final in two years in Atlanta and captured what would be her final professional title, the doubles at the ITF event in Surbiton, England, on grass.

Though she’s leaving the game behind, the memories of what she accomplished on the court are sure to stay with tennis fans everywhere, especially around the US Open.

Follow Van on Twitter: @Van_Sias