McCown was cleared for action Wednesday after passing the NFL's concussion protocol.
The 13-year NFL veteran left the Browns' season opener against the Jets with a concussion after a hit sent him into a spin at the 1-yard line on his first drive of the season. After replacing McCown, Manziel completed 13 of 24 passes for 182 yards, one touchdown and one interception.
Manziel, 22, started for the Browns in Week 2 and completed eight of 15 passes for 172 yards, but also turned the ball over twice on fumbles. The Browns held on for a 28-14 victory over the Tennessee Titans.
The Browns will host the Oakland Raiders on Sunday.
- Christopher Chavez