Merryweather (knee) made his second rehab appearance at Triple-A Iowa on Tuesday, striking out one and giving up no hits and one walk over a scoreless inning.
Merryweather was placed on the 15-day injured list Aug. 27 with right knee tendinitis but was cleared to begin a rehab assignment last weekend. Assuming he checked out fine coming out of his second outing Tuesday, Merryweather could rejoin the Chicago bullpen for the team's four-game series with the Nationals that begins Thursday.