Doug Flach (born August 10, 1970, in St. Louis, Missouri) is a former tennis player from the United States.Flach won two doubles titles during his career. The right-hander reached his highest individual ranking on the ATP Tour on March 21, 1994, when he reached World No. 108. He defeated Andre Agassi (seeded third) in the first round at Wimbledon in 1996 but lost in the third round. He also defeated Agassi in 1997 at Washington, D.C.