49ers provide updates on Trent Williams, George Kittle and Christian McCaffrey, who calls new back ailment 'not serious' ahead of Seahawks showdown

The status of multiple 49ers Pro Bowlers is unclear as San Francisco prepares for Saturday's showdown against the Seattle Seahawks.

Head coach Kyle Shanahan provided injury updates on players ahead of a Tuesday walkthrough, including Trent Williams, Christian McCaffrey and George Kittle.

Williams and McCaffrey didn't participate in the walkthrough, which is normal for both veterans for the first practice session of the week. But they both have injury designations. 

McCaffrey was listed on the practice report with a previously undisclosed back injury. Shanahan declined to clarify when the injury surfaced, but told reporters "it’s just stiff."

McCaffrey added that the injury is "not serious," indicating that his playing status for Saturday's game is not at risk. Considering his injury history, it's a situation worth monitoring for the rest of the week. 

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Williams, meanwhile, is dealing with a hamstring injury that he sustained on the first possession of San Francisco's win over the Chicago Bears Sunday night. Shanahan told reporters that Williams has not been ruled out for Saturday's game. 

"We’re not sure how long," Shanahan said when asked how long Williams would be sidelined. "We’ll give him a shot this week. We’ll see."

Kittle, meanwhile, was back at practice as a limited participant with a sprained ankle. His participation was an encouraging sign for the 49ers after he missed Sunday's game with the injury that he sustained the previous Monday night in a win over the Colts. 

Shanahan, however, wasn't ready to declare Kittle ready to face Seattle.

"I wouldn’t assume that," Shanahan said when asked if Kittle has a good chance to play. "We’re barely moving today. It’s a walkthrough. With the short week we’ve got, we won’t be doing much all week.

While McCaffrey sounds on track to play, the status of Williams and Kittle is less clear. With the No. 1 seed and the first-round playoff bye the comes with it at stake on Saturday, expect all of them to play if there's anyway they can go.