Harris (undisclosed) didn't play in Thursday's preseason game against San Francisco, but coach Jim Harbaugh said afterward that the wideout should practice this weekend, Kris Rhim of ESPN.com reports.
It sounds like Harris is dealing with a minor injury. Quentin Johnston (lower body) also missed Thursday's exhibition, leaving rookie Brenen Thompson to fill in as a starter opposite Ladd McConkey. Come Week 1, it'll likely be McConkey, Johnston and Harris as the top three.