 Rothenberg had no experience with soccer until the age of 28, when he came into contact with the nascent North American Soccer League while serving as a lawyer for Jack Kent Cooke.Cooke, who owned several sports teams, had also acquired the NASL's Los Angeles Wolves, a short-lived team that lasted only until 1968.Almost ten years after the folding of the Wolves, Rothenberg headed an investment group that bought the Los Angeles Aztecs, a newer club in the same league, but he sold the team after three seasons in 1980, thus escaping the later collapse of the league.