Maria Sharapova retired from tennis by 2000.
Maria Sharapova . Since February 2007 , she has been a United Nations Development Programme Goodwill Ambassador , concerned specifically with the Chernobyl Recovery and Development Programme . The WTA Finals ( formerly known as the WTA Tour Championships short : WTA Championships ) , is a professional tennis tournament played annually at the end of the season for the top-ranked players on the Women 's Tennis Association ( WTA ) tour .