Melanie Oudin is retiring from professional tennis, eight years after her captivating run to the US Open quarterfinals as a teenager.

The 25-year-old American announced her decision in a series of posts on Twitter on Friday.

Oudin has dealt with a series of health problems in recent years. Those included a diagnosis of rhabdomyolysis, a muscle-damaging condition that can be caused by intense exertion, in 2013, and a procedure to address occasional episodes of an accelerated heartbeat the following year.

She has not played a professional match since entering lower-level ITF tournaments last season.

Oudin has been ranked as high as 31st but is now outside the top 400.

She won one WTA singles title, on grass at Birmingham, England, in 2012, and teamed with Jack Sock to win the US Open mixed doubles championship in 2011. Oudin also was a member of the U.S. Fed Cup team.

At the 2009 US Open, as an unseeded and unknown 17-year-old from Marietta, Georgia, the 70th-ranked Oudin pulled off a series of stunning results, upsetting four higher-ranked women -- including Maria Sharapova and Beijing Olympic gold medalist Elena Dementieva -- to become the youngest quarterfinalist at Flushing Meadows since Serena Williams in 1999.

The vivacious teen whose shoes were stamped with "BELIEVE" during those memorable two weeks in New York closed her three-tweet message to fans and others Friday with that very same word, in all capital letters for emphasis.