The Pirates were held to six hits in a 4-1 loss to the Reds in Cincinnati.
Dario Agrazal allowed six hits and three runs in three-and-two-thirds innings to take the loss.
Jose Osuna had a pinch-hit double for the Bucs' only extra-base hit.
Luis Castillo got the win for Cincinnati.
The Pirates have lost 10 of their last 11 games.