Career
Greenberg was ranked United States. Number. 5 in singles in 1943 and 1944 and also in the top 10 in three other years. Greenberg"s three doubles titles still rank first all-time in Big Ten history.
He led the Northwestern Wildcats to the Big Ten team championships in 1940 and 1942.
Greenberg was also a singles quarterfinalist at the United States. Championships in 1942, 1943, 1944, and 1945. In 1943 at the tournament in Cincinnati, Ohio, Greenberg reached the singles and doubles finals but lost the singles final to future International Tennis Hall of Fame inductee Bill Talbert.
Greenberg had partnered with Joe Scherr to reach the final. Greenberg has been inducted into:
the Chicago Jewish Sports Hall of Fame (1982),
the United States Tennis Association/Midwest (formerly Western Tennis Association) Hall of Fame (in 1990),
the Northwestern University Athletic Hall of Fame (2000), and
the Chicago Tennis Hall of Fame (2004).