Joe Flacco has resumed throwing and is "moving toward" a return to practice after missing the first three preseason games with a back injury, Baltimore Ravens head coach John Harbaugh announced Tuesday, according to ESPN's Jamison Hensley.

Harbaugh once again said he's confident Flacco will be ready for the Ravens' Sept. 10 season opener against the Cincinnati Bengals.

Related: Ravens' Harbaugh promises Flacco will be ready for Week 1

"He's moving toward practice," Harbaugh said. "Just when the docs clear - which we don't know that date (and) when that's going to happen right now. We believe it's going to be real soon and in time to prepare for Cincinnati. And then he'll be out there."

Harbaugh added he's "very optimistic" receiver Breshad Perriman will also be ready for Week 1 after being sidelined for the past month with a hamstring injury, according to Hensley.