In 1939, he became the second American to win the French championships (after Don Budge). Only seven American men in the history of the French Open have won the singles title.
Karoly Mazak ranked McNeill as World No. 4 for 1940 in his amateur-pro combined rankings. There were no "official" amateur rankings during WW2 - McNeill reached as high as World No. 7 in Gordon Lowe's amateur rankings list in 1939.