SAN FRANCISCO (KTVU) - The San Francisco 49ers suffered another injury blow, when they had to put pro bowl cornerback Richard Sherman on the injured reserve list.
NFL Network reported that it was an old calf strain that flared up again, but Sherman is expected to quickly return.
The new NFL IR rules mandate that Sherman must sit out at least three games.
Head coach Kyle Shanahan not previously mentioned the injury, either in the news conference immediately following Sunday's loss to the Arizona Cardinals or on Monday.
The 32-year-old Sherman starred at Stanford University, before becoming one of the NFL's top cornerbacks with the Seattle Seahawks.
He signed a 3-year deal with the 49ers, beginning with the 2018 season.
Sherman had recently revealed that he is talking with the 49ers about an extension.
The 49ers already have wide receiver Deebo Samuel on the injury reserve list, as he recovers from a fracture in his left foot.
In Sunday's game, star tight end George Kittle hyperextended his left knee, but still played almost every down.
Shanahan said he would wait until Wednesday, to see how Kittle felt and whether if he could play this coming Sunday, on the road against the New York Jets.
The 49ers will likely start Emmanuel Moseley at one cornerback position, but with Sherman sidelined, it's unclear who will defend the other side. Ahkello Witherspoon is currently in concussion protocol, according to The Athletic sports website.
Witherspoon must now concussion tests, before he can return to the field.
Meanwhile, another cornerback Jason Verrett is dealing with an hamstring issue.
With the team thin at cornerback, the 49ers worked out four CBs on Tuesday: Tino Ellis (Maryland), Marquis Bridges (North Dakota State), Christian Angulo (Hampton), and Brian Allen (Utah).
The 49ers ended up signing Allen, who was drafted by the Pittsburgh Steelers in the 5th round in 2017.
Allen has the size the 49ers covet. He is 6 feet. 3 inches tall, and weighs 215 pounds.
He spent last season on the Seattle Seahawks practice squad.
The 49ers also promoted DB Dontae Johnson from the team's practice squad to the 53-man, active roster.