SEATTLE — The Seattle Seahawks put starting right tackle George Fant on injured reserve Saturday, another blow to an already challenged offensive line.

Fant, 32, will sit out at least the next four games, making him eligible to return as early as Week 7. He’s dealing with a knee injury he sustained in the first quarter of the Seahawks’ opener, which sidelined him for the rest of that game as well as their win last weekend over the New England Patriots.

Seattle listed Fant as a limited participant in all three practices this week before ruling him out for Sunday’s game against the Miami Dolphins.

The Seahawks are now down to their third option at right tackle in Stone Forsythe, who is expected to start again in Fant’s absence. Forsythe, a 2021 sixth-round pick, finished 32nd among 60 qualifying tackles last week in pass block win rate (84.6%).

“I thought Stone played well,” coach Mike Macdonald said. ” … I think the second half on, from the Denver game through New England, I thought he’s doing a lot of nice things. … He’s ready to go.”

Through two weeks, the Seahawks rank last in PBWR (38.5%).

Fant had been starting in place of Abe Lucas, who remains on the physically unable to perform list after offseason knee surgery. He’s eligible to return as early as Week 5, but Seattle has been preparing to be without Lucas until at least midseason.

The Seahawks signed McClendon Curtis off their practice squad to reinforce their tackle depth. They also elevated inside linebacker Patrick O’Connell and outside linebacker Tyus Bowser from their practice squad for Sunday’s game and re-signed safety Marquise Blair to their practice squad to fill the open spot.

In addition to Fant, Seattle had already ruled out outside linebacker Uchenna Nwos. Running back Ken Walker III and inside linebacker Jerome Baker are doubtful. Macdonald said Friday he’s “very confident” that Walker, who’s dealing with an oblique injury sustained in the opener, will be back for Seattle’s Monday night game against the Detroit Lions in Week 4.