SANTA CLARA, Calif. — Assistant coach Andre Patterson said this week he'd rather not use the word "depleted" to describe the Vikings defensive line, but that's the reality for Sunday's game in San Francisco.

They're down all four starters, with defensive tackle Dalvin Tomlinson placed on the reserve/COVID-19 list earlier this week. Defensive end Everson Griffen was placed on the non-football illness list on Friday amid his indefinite leave from the team while undergoing mental health treatment. Nose tackle Michael Pierce and defensive end Danielle Hunter remain on injured reserve.

The Vikings have eight defensive linemen available in San Francisco; only two — D.J. Wonnum and Armon Watts — have previously started games for Minnesota this season. Sheldon Richardson is expected to start, possibly at defensive end. Defensive tackle James Lynch could get his first NFL start against the run-heavy 49ers.

Also available are defensive ends Patrick Jones, Eddie Yarbrough and Tashawn Bower, who was re-signed off the Patriots practice squad this week. Defensive tackle T.J. Smith was elevated from the practice squad.

Defensive end Kenny Willekes remains on the practice squad. He has been cleared to return, but has not played while still recovering from a COVID-19 infection. Safety Josh Metellus is officially active in San Francisco after missing the Packers game because of COVID isolation.

San Francisco's running game will return starter Elijah Mitchell from a one-game absence due to finger surgery and a rib injury. The 49ers defense is bolstered by the return of linebacker Dre Greenlaw.

Vikings' inactives: QB Kellen Mond, WR Ihmir Smith-Marsette, CB Harrison Hand, LB Chazz Surratt, S Cam Bynum (ankle) and G Wyatt Davis (ankle)

49ers' inactives: RB JaMycal Hasty (ankle), DL Maurice Hurst (calf), DE Jordan Willis and OL Colton McKivitz