Pro Bowl guard Mike Iupati sustained a sprained left medial collateral ligament in his left knee and is expected to miss some playing time, a source told CSNBayArea.com on Monday.
Iupati sustained the injury in the third quarter of the 49ers' 23-20 loss to the New Orleans Saints when running back Frank Gore rolled onto his leg as Gore was being tackled by Saints nose tackle Brodrick Bunkley for no gain.
Iupati's knee will not require surgery and is not considered a season-ending injury. Veteran Adam Snyder, a nine-year veteran with 83 career starts, replaced Iupati on Sunday. He is likely to start next Monday night against Washington.
The 49ers' offensive line -- left tackle Joe Staley, left guard Iupati, center Jonathan Goodwin, right guard Alex Boone and right tackle Anthony Davis -- made every start as a unit since the beginning of the 2012 season. That streak of 29 consecutive games includes three playoff games.