Kyle Juszczyk will miss a few weeks and the 49ers have no other fullback

Kyle Juszczyk has a hyperextended knee and a bone bruise and will miss "a few weeks," Kyle Shanahan said on his Monday conference call. Marques Sigle has a high ankle sprain and will miss time as well. Upton Stout has a sprained AC joint in his shoulder and is day to day.

All three started Sunday's 24-14 win over Denver. None of them finished it.

Juszczyk, a few weeks. Adam Schefter of ESPN reported earlier Monday that an MRI showed a knee sprain and a bone bruise, and he put the absence at two to three weeks. Shanahan did not put a number on it. Juszczyk was hit on the knee at the end of a 16-yard catch with 14:03 left and was ruled out. He had played 27 of San Francisco's 66 offensive snaps. The 49ers play at Seattle on Sunday, host Washington on Monday, Oct. 19, play at Atlanta on Oct. 25, and then have their bye.

His snaps go to the tight ends. Asked who steps in, and whether Brayden Willis takes over the role, Shanahan answered with three names: "Yeah, Luke and Brayden and Kittle." He called Luke Farrell, Willis and George Kittle "pretty interchangeable," said the injury will "definitely get Brayden some more ops," and added, "Brayden's been ready for this role." Jake Tonges did that work the last couple of years, Shanahan said, and the club lost him in Week 1. Tonges is on injured reserve.

Against Denver, Kittle played 60 offensive snaps, Farrell 29 and Willis 11. Willis also played 22 snaps on special teams. The club's roster page lists one fullback across the 53 and the practice squad, and he is the one with the bone bruise.

Sigle, a high ankle sprain. Shanahan said he will miss time and attached no range. On Sept. 21, when Demarcus Robinson and James Thompson Jr. both had high ankle sprains, he said three weeks at best and up to six. Robinson went on injured reserve five days later. Thompson stayed on the 53 and has not played since.

Sigle was hurt twice on Sunday. He left early in the third quarter with a stinger and came back, per Nick Wagoner of ESPN, then hurt the ankle covering the kickoff with 2:15 left. He played 45 of 66 defensive snaps and made six tackles. Malik Mustapha played 21 snaps, and Wagoner reports that Mustapha takes the starting job beside Ji'Ayir Brown until Sigle is back.

"He did a lot of good stuff last year, but I think he has taken it to another level," Shanahan said of Sigle.

Stout, day to day. "We'll have to manage him through the week to see if we can get him to Sunday," Shanahan said. Stout hurt the shoulder in the third quarter, returned with 2:07 left and went out again. He played 36 of 66 snaps. Shanahan gave two names if Stout cannot play. Ephesians Prysock, inactive against Denver, is a candidate to be activated: "Yeah, definitely." Nate Hobbs, on injured reserve since Aug. 31 with a groin injury, "can be an option too," Shanahan said. "Got to see exactly where his rehab's at. I know he's getting close." Wagoner expects a third arrangement, Deommodore Lenoir in the slot in nickel packages with Jack Jones outside. Jones played 14 defensive snaps against Denver.

Mykel Williams could be up. His practice window from the physically unable to perform list opened last week, and Seattle is the first game he is eligible to play. Shanahan said "hopefully we can get him activated at the end of the week," and then, "it depends how the week goes." Williams did some team drills last week and will again this week, Shanahan said. The 53 is full, so activating him costs somebody a spot. Neither the club's transaction log nor its roster page showed a move on Monday afternoon.

Bosa and Thompson, probably not this week. Shanahan said he is "probably not expecting" Nick Bosa or Thompson back for Seattle. Bosa has not played since Sept. 20 against Miami, the game in which Thompson sprained his ankle. Christian Kirk will not be back at practice this week. "Hopefully next week," Shanahan said.

Evans, no setback. Mike Evans played 39 snaps on Sunday with a rib injury and caught five passes for 76 yards. Shanahan said he had been told of "no setbacks."

The first Week 5 practice report is due Wednesday.

Sources: Kyle Shanahan's Oct. 5 conference call, from the club's transcript as posted by 49ers Webzone and the reports of Nick Wagoner (ESPN) and David Bonilla (49ers Webzone); Adam Schefter (ESPN) on the MRI; the official Week 4 game book for the lineup card, snap counts, tackles, inactives and injury times; the 49ers' roster page and transaction log; Shanahan's Sept. 21 conference call, from the transcript at 49ers Webzone.