He was named the 1950 American Horse of the Year and Champion Three-Year-Old Male.
Middleground was ridden throughout his career by 16-year-old apprentice jockey Bill Boland, and he was trained by Max Hirsch, both future U.S. Hall of Fame inductees.
As a two-year-old in 1949, Middleground won the Hopeful Stakes and came third in the Arlington Futurity.
Five time Kentucky Derby winning jockey Eddie Arcaro had the chance to ride Middleground, but he chose to ride Hill Prince instead, who finished second.
In the 1950 Jerome Handicap, Middleground broke a bone in his foot and was retired.