A connector for connecting a fluid passage device, such as may be provided by a luer taper, and an injection site having a thin diaphragm, and method of forming a medical coupling site connection between the fluid passage device and the injection site. The connector includes a reduced diameter cannula for engaging the thin diaphragm sufficiently to open the thin diaphragm to establish an open fluid passage. The connector is further disclosed as including an enlarged annular land portion surrounding the cannula for forming an interference fit within a retention portion of the injection site.