The following year, Middleground started the year with second-place finishes both the Withers Stakes and Wood Memorial.
He then won the Kentucky Derby, only the second horse to win it with an apprentice jockey after his sire Bold Venture who won with jockey Ira Hanford. 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.
After the Kentucky Derby, Middleground finished second to Hill Prince after a rough trip in the Preakness Stakes, and won the Belmont Stakes.
In the 1950 Jerome Handicap, Middleground broke a bone in his foot and was retired.
Retirement and stud career
Middleground was retired to stud at King Ranch in 1951. He sired 101 winners and 7 stakes winners in his stud career, including Resaca, Chistosa, and Here and There.