Jeff Zrebiec of The Baltimore Sun reports that Harbaugh said Daniels might be ready to return for next week's game.
Daniels, 31, has 27 catches for 275 yards and three touchdowns in his first season with the Ravens. He spent the first eight seasons of his career with the Houston Texans, with whom he amassed 4,617 yards and 29 touchdowns en route to a pair of Pro Bowl appearances.
Baltimore's offense has improved from No. 25 in points and No. 29 in yards last season to No. 6 and No. 7 this season.
The Ravens are 5-2 and in first place in the AFC North. They play the Bengals in Cincinnati on Sunday at 1 p.m.
- Paul Palladino