Felipe Vazquez held on in the ninth for his 13th save in 17 opportunities. Tucker Barnhart singled with two outs and pinch-runner Billy Hamilton stole second base before Joey Votto struck out swinging.
Tyler Glasnow and Kyle Crick also pitched one scoreless inning of relief.
A sacrifice fly by Scooter Gennett in the third inning drew the Reds into a 1-1 tie and they went ahead in the fourth, scoring a run on a throwing error by Kuhl.
Pittsburgh scored the game’s first run when Gregory Polanco grounded into a double play in the second inning.
The Reds lost despite outhitting the Pirates 7-5. They were 0 for 11 with runners in scoring position and stranded 10 baserunners.
Cincinnati’s Jose Peraza had two hits.
Reds: RHP Homer Bailey (right knee inflammation) stopped his rehab assignment at Triple-A Louisville. On the disabled list since May 30, Bailey made one start for Louisville and was tagged for five runs in three innings Monday.
Reds: Luis Castillo (4-7, 5.79 ERA) has lost his last three starts with a 7.47 ERA.
Pirates: RHP Ivan Nova (3-5, 4.68) beat the Cubs at Chicago last Sunday in his return from the DL, allowing one run in 5 2/3 innings after being out with a sprained right ring finger. He is 3-7 lifetime against Cincinnati.