Rod Barajas hit a two-run homer off Washington closer Henry Rodriguez with two outs in the ninth to lift the Pittsburgh Pirates to a 5-4 victory on Tuesday night.
The veteran catcher, mired in a season-long slump, drilled a shot down the left field line that sailed a few rows into the seats for his first home run and RBIs of the year.
The Nationals went ahead 4-3 after Adam LaRoche's two-run blast in the top of the ninth off Pittsburgh closer Joel Hanrahan.
Alex Presley singled with one out in the bottom of the ninth off Rodriguez (1-2) and moved to third on a pair of wild pitches before Barajas broke through.
Tony Watson (2-0) earned the victory after replacing Hanrahan.
Barajas, brought in during the offseason to give the Pirates some needed pop at the plate, has struggled to find his footing. He was hitting .131 when he stepped into the box in the ninth and was booed heavily after popping up during his previous plate appearance in the seventh.
Rodriguez, perhaps unsettled after walking Presley then letting him advance to third by uncorking two wild pitches, threw a fastball that Barajas hit into the seats for his first home run since last September when he played for the Los Angeles Dodgers.
Barajas raised his arms in triumph and nearly slipped rounding first base before getting mobbed by his teammates after crossing the plate.
Andrew McCutchen hit his first homer of the season for the Pirates and Garrett Jones added his fourth. Neil Walker gave Pittsburgh a 3-2 lead in the bottom of the eighth with a sacrifice fly off Washington reliever Tyler Clippard.
The lead lasted all of two batters.
Ryan Zimmerman, playing in his first game since April 20 after spending more than two weeks on the disabled list with inflammation in his right shoulder, singled off Hanrahan and LaRoche smashed a 97 mph fastball from Hanrahan just over the wall in center.
The Nationals, who have climbed to the top of the National League East thanks to nine wins in one-run games, turned to Rodriguez. He struggled against the bottom third of one of baseball's weakest lineups.
Washington rookie outfielder Bryce Harper went 1 for 4 with a double while starting in right field in place of Jayson Werth, who was placed on the 15-day disabled list Tuesday after breaking his left wrist in a loss to Philadelphia on Sunday.
Werth will be out at least three months, meaning Harper is likely here to stay. He certainly appears ready. The 19-year-old is batting .300 with six doubles in just nine games.
The late struggles by the closers was in stark contrast to the work done by both starters.
Washington's Edwin Jackson was stellar, giving up three hits in seven innings, striking out five and walking one. He retired the final 10 batters and needed just 91 pitches to deal with baseball's lowest scoring team.
Pittsburgh's A.J. Burnett, lit up for 12 runs in 2 2-3 innings by St. Louis last Wednesday, bounced back with the kind of performance the Pirates were looking for when they acquired him in a trade with the New York Yankees in February.
The 35-year-old gave up a solo homer to Wilson Ramos leading off the third and an RBI single by Rick Ankiel in the fourth. Otherwise he was dominant and grew stronger as the night wore on, allowing two runs and six hits in eight innings, walking one and striking out 10.
NOTES: The Nationals are 9-5 in one-run games this season, with all five losses coming on the road ... The series continues on Wednesday. Ross Detwiler (3-1, 1.59 ERA) will start for the Nationals against Pittsburgh's Erik Bedard (2-4, 2.65) ... Pittsburgh's Pedro Alvarez is 0 for 8 since moving to cleanup on Saturday.