Stepanek downed the Frenchman 6-4, 6-4, and at age 32 became the oldest champion on the ATP Tour this season, as well as the oldest Washington winner since Jimmy Connors claimed the crown in 1988 at age 35.
Stepanek won $264,000 with his fifth career title and first since San Jose in 2009 despite coming into the contest with an eight-match losing streak against Top 10 opponents.
Monfils, ranked seventh in the world, dropped to 3-11 in title matches for his career.
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