Key file for vCenter certificate?

I generated a CSR through the vCenter web interface (Administration>Certificate Management>Machine SSL Certificate>Actions>Generate CSR). I submitted the csr and got the certificate back, but I need the private key file. Can anyone tell me where on the vcenter server the csr generation process would have put that by default? Most of the documentation I've seen is for the certificate manager command and uses a switch for the file location, but there isn't much documentation for the web client.

Thanks.