SANTA CLARA, Calif. -- The San Francisco 49ers will be without starting fullback Kyle Juszczyk (knee) and safety Marques Sigle (ankle) for at least a few weeks after they suffered injuries in Sunday's 24-14 win against the Denver Broncos.
Niners coach Kyle Shanahan said Monday afternoon that Juszczyk is dealing with a hyperextended knee with a bone bruise that will keep him out "a few weeks" and Sigle suffered a high ankle sprain that will also cost him extended time.
Cornerback Upton Stout, who also left Sunday's game because of an AC sprain in his shoulder, is day-to-day as the Niners prepare for Sunday's clash with the Seattle Seahawks.
With 14:03 to go, Niners quarterback Brock Purdy scrambled to his left and found Juszczyk open down the sideline for a 16-yard gain. Broncos defensive back Jahdae Barron delivered a big hit to Juszczyk's knee and midsection, and Juszczyk stayed down for a few minutes as the Niners' medical team rushed to help.
Juszczyk was helped to the sideline, where he entered the medical tent before watching the rest of the game on the bench. The 49ers quickly ruled out Juszczyk, who finished with two catches for 28 yards. An MRI performed Monday confirmed the nature of his injury.
Juszczyk, who has been selected to the past 10 Pro Bowls, has four receptions for 55 yards and a touchdown this season. Shanahan said Juszczyk's role will be filled by tight ends George Kittle, Luke Farrell and Brayden Willis, who has the most experience playing a fullback role.
"They're all pretty interchangeable, but it'll definitely get Brayden some more [snaps]," Shanahan said. "Braden's been ready for this role."
Sigle suffered a pair of injuries Sunday, initially departing early in the third quarter because of a stinger. He returned on Denver's next possession but was injured with 2:15 left when he hurt his ankle near Denver's sideline. He did not return, finishing with six tackles.
According to Shanahan, Sigle has taken a big step forward in his second NFL season, ranking fourth on the team in tackles (25) through the first four weeks.
"I think he's been playing his ass off in the run and pass game," Shanahan said. "He did a lot of good stuff last year, but I think he has taken it to another level, just playing a little bit faster, hesitating less, knowing what he's doing and really playing well before that injury."
Malik Mustapha, who has rotated in with Sigle over the past two weeks, will step into the starting role next to Ji'Ayir Brown until Sigle can return from his injury, which can require a three-to-six-week recovery.
Stout hurt his shoulder in the third quarter and jogged to the locker room to be evaluated soon. Stout returned with 2:07 to go but left again and did not return during the Broncos' final few snaps. He also finished with six tackles.
Though Stout is considered day-to-day, the Niners would likely move Deommodore Lenoir into the slot with Jack Jones outside in nickel packages. Rookie Ephesians Prysock provides additional depth at cornerback as veteran Nate Hobbs gets closer to returning from injured reserve, according to Shanahan.
Elsewhere on the injury front, Shanahan said defensive end Nick Bosa (calf) and defensive tackle James Thompson Jr. (ankle) are not expected to return Sunday against the Seahawks.
Defensive end Mykel Williams (knee) is entering his second week of practice as he returns from the physically unable to perform list, and the Niners hope he will be available against the Seahawks.
"Hopefully, he has a good week of practice, and hopefully, we can get him activated at the end of the week, but depends how the week goes," Shanahan said.
