My Redeemer! (Job 19:1-29)

Job continues to consider his life, his struggle, and what he has become.  He has moved from a man who possessing great prestige in society, among the wealthiest, but has been reduced to one who hopes that there is someone who will take his case to the highest court.  In chapter 19 Job moves from one who hopes there is a lawyer/advocate who can plead his case to now clinging to a redeemer.  Why is this is a significant shift for Job?