The San Francisco 49ers ran wild on Monday night, racking up 275 yards on the ground in a blowout victory against the Cleveland Browns to wrap up Week 5, but they’ll be without one of the biggest keys to their rushing attack for at least the next month. Less than 24 hours after fullback Kyle Juszczyk was forced to exit the Niners’ big win on a cart thanks to a leg injury suffered against the Browns, the team has announced the three-time Pro Bowler will be sidelined between four to six weeks because of an MCL sprain. NFL Network reported earlier Tuesday that Juszcyk was set to undergo an MRI to diagnosis his injury, which he sustained in the second half of Monday night’s affair.

San Francisco isn’t likely to veer away from its ground game in the coming weeks now that both of its top two running backs, Matt Breida and Tevin Coleman, are healthy atop the depth chart. But Juszczyk has been lauded for his run blocking as one of the last traditionally utilized fullbacks in the NFL, helping pave the way for Breida and Coleman’s explosive performance against Cleveland. He is also an excellent receiver out of the backfield.

Originally a fourth-round draft pick of the Baltimore Ravens in 2013, the Harvard product spent the first four seasons of his career in Maryland before inking the largest contract for a fullback in league history with the Niners in 2017. Consistently graded as one of the best at his position, the 28-year-old has also contributed six catches for 76 yards this season operating behind Jimmy Garoppolo. Behind his blocking this year, the Niners have averaged 126.2 rushing yards per game.

“He does so many different things in the run game and even the pass game where he brings a different element that not many fullbacks can do,” Garoppolo said Monday night, according to The Mercury News.

Barring a free-agent addition, San Francisco will have to get creative during Juszczyk’s absence, as the 49ers do not currently have another fullback on their roster.