Christian McCaffrey says his back issue is "not serious"

49ers running back Christian McCaffrey didn't practice on Tuesday, but it is nothing that will keep him out of Saturday's NFC West showdown with the Seahawks."It's just stiff," 49ers coach Kyle Shanahan said before practice, via David Bonilla of 49erswebzone.com.McCaffrey was holding his back on the field and stretching it on the sideline during Sunday's win over the Bears. He played 61 of 72 snaps and totaled 27 touches for 181 yards and a touchdown.McCaffrey was succinct when asked whether his back issue was serious."No," McCaffrey said. "Not serious."McCaffrey, who had a back issue earlier this season, per Shanahan, will be in the lineup as the 49ers try to win the NFC West and the No. 1 overall seed."It means a lot," McCaffrey said. "It's a huge game for us, obviously, this week, and our team's intent and focus is to get better today and show up ready to roll on Saturday."