The 49ers' offensive line has been remarkable, not only for its performance over the past three seasons, but for its durability.For the past 29 consecutive games, San Francisco has started the same fab five: left tackle Joe Staley, left guard Mike Iupati, center Jonathan Goodwin, right guard Alex Boone and right tackle Anthony Davis.On Monday night against the Washington Redskins, however, that streak will come to an end. Iupati, who suffered an injury to his left knee late in Sunday's loss to the New Orleans Saints, isn't expected to play Monday night. So, Adam Snyder – the veteran who used to start at right guard before leaving for Arizona in free agency and then returning over the offseason – will start in his place.Originally, it was feared Iupati's injury might be season-ending. However, he's now been diagnosed with a sprained knee. It's not certain yet when he'll be able to return.Iupati -- who has started 58 straight games -- is one of two 49ers starters expected to be sidelined for Monday's game. Cornerback Tarrell Brown, who has a rib injury, will be replaced by nickel corner Tramaine Brock, with newcomer Eric Wright slipping into the No. 3 cornerback...