The Nationals had jumped out to an early lead, John Lannan was grooving and it was looking like Jim Riggleman's squad would leave Pittsburgh with a series win and a .500 record on their six-game road trip.
Then the rain came, and the 19-minute delay that ensued seemed to put a stop to all the Nats' momentum.
Lannan allowed a walk and two straight hits coming out of the delay, the Pirates scored four runs in the fourth inning and they held on for a 4-2 win in the rubber game of this three-game set.
Adam LaRoche gave Washington a 2-0 lead in the first inning with a two-run single up the middle, and Lannan rolled through the first three innings.
But two walks, three hits and a throwing error by Jayson Werth in the fourth allowed the Pirates to take the lead, and they never looked back.
The Nats finish the road trip with a 2-4 mark, and will return home tomorrow to start a seven-game homestand.
More to come.