DENVER -- The San Francisco 49ers will be without two more key starters for at least the next month because of injuries left tackle Trent Williams and linebacker Azeez Al-Shaair suffered in Sunday night's loss to the Denver Broncos.
Coach Kyle Shanahan said Monday that Williams will likely miss four to six weeks with a high right ankle sprain and that Al-Shaair could miss about eight weeks with a sprained MCL in his right knee.
Neither player is expected to require surgery, according to Shanahan. A more precise timetable for Williams won't be known until the swelling in his ankle goes down.
"High ankles are usually, they say four to six [weeks] but sometimes they can be sooner and sometimes they can be longer, so that's why we didn't have an exact date," Shanahan said. "It's too early to tell."
Because of what Shanahan called "pretty bad" swelling, the Niners also will wait to decide on whether to place Williams on injured reserve. Shanahan noted that teams only get a certain number of players (eight) who can go on injured reserve and come back after four weeks per season. And because San Francisco already has at least three players who could return from injured reserve (running back Elijah Mitchell, safety Jimmie Ward and end Jordan Willis) and likely will have to use a fourth spot on Al-Shaair, it would prefer to not do so with Williams.
"We are hoping we don't have to," Shanahan said. "You only get so many of those and we want to make sure we save those. ... We'll see how it goes. If it ends up being we're leaning towards longer, we might have to make that decision."
Al-Shaair's situation is clearer-cut because his injury is comparable to the one Mitchell suffered in a Week 1 loss to the Chicago Bears.
"[It's] very similar to what Elijah did," Shanahan said. "I know we gave Elijah -- our guess was around eight weeks."
Williams was hurt with 9:53 left in the third quarter after Broncos defensive tackle D.J. Jones rolled into the back of his right leg. A cart was brought out to take Williams to the locker room but he declined it and hobbled to the tunnel with the help of Niners medical personnel.
Al-Shaair's injury came with 4:43 left in the second quarter.
The Niners initially called upon Jaylon Moore, a fifth-round pick in the 2021 NFL draft, to step in for Williams but later switched to Colton McKivitz, who was a fifth-round choice in the 2020 NFL draft. McKivitz is likely the next man up to replace Williams and would have been first against the Broncos had he not been dealing with an ankle injury of his own last week in practice, according to Shanahan.
The 49ers are also expecting to get lineman Daniel Brunskill back in practice this week after a hamstring injury cost him the first three games, though Shanahan indicated he won't be a candidate to replace Williams.
"I'd expect McKivitz to go," Shanahan said. "That's probably what would have happened last week from the beginning if he didn't get banged up in practice and miss all those reps. Most likely it will be that and hopefully we get Dan back to possibly help us out inside."
Demetrius Flannigan-Fowles stepped in for Al-Shaair against the Broncos, posting three tackles in the loss.