49ers’ Christian McCaffrey battling injury ahead of Saturday showdown with Seattle

SANTA CLARA — Christian McCaffrey’s back is aching, understandably so. His 399 touches are the most ever in a 49ers season.

The 49ers’ offensive workhorse has yet to miss a game this season, but a “stiff” back kept him from Tuesday’s light practice at Levi’s Stadium, ahead of Saturday’s high-stakes 5 p.m. kickoff against the Seattle Seahawks for the NFC playoffs’ No. 1 seed.

McCaffrey said his back issue is “not serious” and seemed upbeat during his routine yet lengthy media session at his locker.