ESPN's Adam Schefter first reported the news on Twitter:
More brutal injuries: 49ers wide receiver Mario Manningham tore his ACL and PCL Sunday night vs. Seattle. Done for season.— Adam Schefter (@AdamSchefter) December 25, 2012
A torn ACL and PCL will not only take Manningham out for the season, but it could hurt his ability to play at full strength next season.
This news comes on the heels of a devastating 42-13 defeat at the hands of the Seattle Seahawks on Sunday Night Football.
Through 16 weeks of football, the acquisition should be considered a success.
Manningham was second on the team with 42 receptions and third with 449 receiving yards. Michael Crabtree leads the team in both categories.
He also showed the ability to stretch the field with six plays of at least 20 yards this year.
However, the injury means that the 49ers will need others to step up in Manningham's absence. This is especially true with receiver Kyle Williams out for the year with a torn ACL.
Moss should assume the starting job, while Ted Ginn should see more of the field on offense. First-round pick A.J. Jenkins should also have a bigger role, despite not catching a single pass all year and only being active for a couple of games.
Despite the loss to the Seahawks, San Francisco still leads the NFC West and will be able to clinch the division with a Week 17 win over the Arizona Cardinals. In addition, a loss by the Green Bay Packers could give the team a first-round bye.
Still, adjustments will need to be made in order to recover from the latest loss of one of the more dynamic players on the roster.