SANTA CLARA, Calif. — San Francisco safety Dashon Goldson, defensive lineman Ray McDonald and right tackle Jonas Jennings will all miss the 49ers' game against Seattle on Sunday.

Both Goldson and McDonald went down with knee injuries during last week's loss to the New York Giants. McDonald was the 49ers' starting left defensive end, while Goldson has played extensively as a backup defensive back this season.

Jennings, the oft-injured lineman who has missed more games than he has played in four seasons with the 49ers, will be out one more week while recovering from a dislocated right shoulder. Jennings was discouraged Wednesday after learning he would be held out of Sunday's game, the 49ers' first under interim coach Mike Singletary.

"I'm just doing what I have to do," said Jennings, who has played in just 23 of the 49ers' 55 games since signing a lucrative free-agent deal in 2005. "It's frustrating, just going through the same thing again and again, but I'm not trying to be insubordinate."

Jennings was injured in the 49ers' first meeting with Seattle this season, a 33-30 overtime victory for the Niners.

Rookie receiver Josh Morgan, safety Mark Roman and kick returner Allen Rossum all missed Wednesday's practice to rest groin injuries, and safety Michael Lewis sat out with a knee problem. Cornerback Nate Clements was limited while resting his ribcage injury, but all five players are expected to be ready for Sunday.