Allocate Random case SQL 2008

I have a list of teams in one table and list of cases in another table. I have to allocate a random case to each one of the members in the team. What is the best way to generate random case number for each team member. I have read about NewID() and CRYPT_GEN_RANDOM(4) functions. I tried using them but not getting unique number for each team member. Can some one please help me. Thanks for your time. I am using SQL 2008.