SANTA CLARA, Calif. -- The San Francisco 49ers are getting receiver relief in the form of Mario Manningham this week against Carolina and his return couldn't come soon enough.The 49ers have gotten virtually no production from their receivers beyond Anquan Boldin. Mannigham, out since last December with knee injury, will step in and become an immediate part of the passing attack along with Boldin (who is probably the happiest man in San Francisco to see Manningham come back because he may see less double teams) and tight end Vernon Davis.