SANTA CLARA -- Left tackle Joe Staley practiced Thursday with the 49ers, four days after spraining his right knee in their 23-13 win over the St. Louis Rams.

Staley missed Wednesday's practice and figured to be unlikely to play in Sunday's home game against the first-place Seattle Seahawks. His participation Thursday offered optimism that he could keep alive a starting streak dating back to the 2011 season opener.

Staley has been selected to the past two Pro Bowls. Alex Boone moved over from right guard to replace Staley once he got hurt in Sunday's opening series.

Left guard Mike Iupati continued to do individual conditioning. He's been out since spraining his left knee in a Nov. 17 loss at New Orleans.

Rookie tight end Vance McDonald (ankle) was not participating in team drills at the start of practice.

Defensive tackles Justin Smith (shoulder) and Ray McDonald (ankle) were practicing, as were wide receivers Michael Crabtree (Achilles) and Quinton Patton (foot). Neither Crabtree nor Patton have been on recent injury reports and look fully healthy.

Cornerback Tarell Brown (ribs) practiced for a second straight day in a non-contact jersey. Defensive coordinator Vic Fangio said Brown would be eased back into action when capable, thus it's likely Tramaine Brock would earn a third straight start at right cornerback.