Niners RB Kendall Hunter out for season

Mike Garafolo, USA TODAY Sports | USATODAY

San Francisco 49ers running back Kendall Hunter will miss the rest of the season with a left ankle injury suffered in Sunday's game against the New Orleans Saints, according to a person informed of the prognosis for Hunter.

The person, who spoke to USA TODAY Sports on condition of anonymity because the 49ers haven't yet announced how long Hunter will be sidelined, did not specify the injury. The Niners said only Hunter had suffered an ankle injury on Sunday.

Hunter, a fourth-round pick last year, had 371 yards and two touchdowns on 72 carries in San Francisco's first 11 games this season as a backup to starting running back Frank Gore. He's now the second 49ers player lost for the season this week, joining wide receiver/returner Kyle Williams, who tore his ACL.

The loss of Hunter means the Niners will need rookie LaMichael James and veteran Brandon Jacobs to step up. James has yet to dress for a game this season.

Jacobs, who signed with San Francisco after being cut by the Giants, got his first carry of the season on Sunday. It was a rush for 1 yard.

Jacobs has been frustrated with how little he's been used this year after suffering a knee injury in the preseason. He's about to see his workload increase.

A possible replacement for Hunter on the active roster would be rookie running back Jewel Hunter, who is currently on the non-football-injury list and must be activated this week at the end of his three-week window to return.

Hunter and Williams were hurt on the same play during the second half of Sunday's game. Both had to be helped off the field and were taken by cart to the locker room. They were injured on a running play in which Hunter carried the ball for a 2-yard gain late in the third quarter.

Williams said Monday he will miss the rest of the season with a torn ligament in his left knee sustained in Sunday's win at New Orleans. He posted on his Twitter account that he has a torn anterior cruciate ligament in the knee. Surgery would be the likely next step.

"Regret to inform y'all I will be out for the season with a torn ACL," Williams tweeted. "Not how I saw things playing out. This is just another obstacle I will have to climb to get back. Looking forward to the challenge!! Love all true fans your prayers are much appreciated."

Coach Jim Harbaugh provided no updates Monday, but did say it appeared Williams was hurt before any contact was made when his foot stuck in the ground.

"We'll see. We haven't got the final report and we'd wait 'til we get that before we brief Kyle and some of the others," Harbaugh said. "It was a hard-hitting game. It took a toll."

Harbaugh added: "There's a good chance there'll be some new active guys on Sunday. Yeah, I send that message to some of our young guys, some of our inactive guys that the opportunity is coming. You say that every week to them, 'Be prepared, be prepared.'

"You'd rather be prepared for your opportunity and have it not come than have your opportunity come and not be prepared. To both those youngsters' credit, and others who have been working extremely hard for their opportunity, we feel good and excited that a couple of those youngsters will get that opportunity."

Contributing: The Associated Press