Williams' left ankle was broken during the team's 29-3 loss Sunday night to the Seattle Seahawks.
In the wake of the injury, 49ers linebacker Patrick Willis said that the NFL should evaluate its stance on cut blocks.
"I feel like, as a linebacker or a D-lineman, any cut -- it's a man sport, be a man, hit me up high," Willis told CSNBayArea.com. "Hit like rams. You don't see a ram going and cutting another ram's legs. They hit head to head, pad to pad."
To replace Williams, the 49ers added fullback Owen Marecic. He is the first former Stanford player coached by Jim Harbaugh to be on Harbaugh's 53-man roster with San Francisco since he took over in 2011. After the Cleveland Browns drafted Marecic in the fourth round in 2011, Harbaugh said he'd tried to get him.
While the strong-blocking Marecic was brought in to help a struggling running game, the 49ers are thin at nose tackle. Glenn Dorsey, who was rotating with Williams, is now the starter. San Francisco will likely keep its eyes open at the position.
Also Monday, the 49ers tried out linebackers David Hinds and Ty Powell.