A report from Mark Barrows indicates Iupati sprained his left MCL when Frank Gore fell on his leg in the third quarter of Sunday's game against the New Orleans Saints. He left the field with the assistance of trainers and was taken to the locker room for further evaluation. Iupati did not return.
The 49ers will likely turn to rotational offensive lineman Adam Snyder to start in Iupati's absence. He has been a long-standing member of the team, appearing in over 100 games since being drafted by the organization in the third round of the 2005 NFL draft.
Losing Iupati is a major blow to a team coming off back-to-back losses. They have a relatively easy two-game streak against the St. Louis Rams and Washington Redskins before a vital meeting with the Seattle Seahawks. The organization will hope Iupati is at full strength for the Week 14 game.