proxy - Nginx proxy_pass to a password protected upstream -

I want to pass the request to an upstream server. The original url password is not protected, but the upstream server is

I need to inject a basic Auth username / password in the request, but get errors when this happens:

  upstream support backend {server username: password@support.yadayada Com; }  

and

  upstream support backend {server support.yadayada.com; } Location / Deliver {proxy_pass http: // username: password @ backend support; }  

You get the proxy_set_header authorization "Basic ...."; where .... has a base of 64 users: pass .