As it had all series, the rain wreaked havoc with the Washington Nationals in Pittsburgh.

Friday's scheduled series opener was postponed until Monday night — causing the Nationals to privately wonder why it wasn't an afternoon getaway game. Then Saturday, Washington starter Livan Hernandez blamed an abrupt end to a one-hour, 11-minute delay to start the game for the Pirates' five-run first.

On Monday, Washington had a 2-1 lead heading into a 21-minute rain delay, but it quickly deteriorated when the Pirates scored three runs over the first three batters after the delay in what ended in a 4-2 Pittsburgh win.

"I was shocked when (crew chief Phil Cuzzi) called (for a stoppage), but it doesn't matter because you've got to make pitches and I didn't," starter John Lannan said. "I got too many balls up in the strike zone."

Pirates starter Paul Maholm came out of the fourth-inning rain delay much better than Lannan. Maholm said he relaxed in the clubhouse and watched the Penguins-Lightning NHL playoff game during the delay.

Lannan (2-2) rode a stationary bike but emerged to promptly walk Steve Pearce and allow Brandon Wood's two-run double, erasing the Nationals' lead.

Lannan was ahead 0-1 on Pearce before the rains came.

"We were still in decent shape, but then Wood got the big hit," Nationals manager Jim Riggleman said. "I thought John's pitch was a pretty good pitch. I saw a replay and it looked like it was in a decent spot but Wood has good power and put a good swing on it."

Wood's double in his first game for Pittsburgh was part of a four-run fourth inning that gave the Pirates their first lead.

"It's nice you get the fist hit and the first couple RBIs out of the way and can just go play some baseball from here," said Wood, picked up on waivers from the Los Angeles Angels on Friday.

"It's just one game and you never know how things go," Wood added. "I'm just going to keep the same mentality and just have fun. The guys were great. I'm fortunate to be around these guys because that was some fun coming through the dugout after that hit."

Announced paid attendance was 12,457, but only about 2,600 made it through the turnstiles on what wasn't originally a scheduled game night. Also contributing to the poor showing was the rain and the Penguins playoff game.

Maholm (1-3) retired the final 13 batters he faced in seven strong innings. He allowed four hits and two walks with eight strikeouts in winning for the first time this season.

After Adam LaRoche's two-run single in the first inning, Maholm faced only two over the minimum the rest of the way. Six of the 15 runs Maholm has allowed this season have come in the first inning, but he did not allow a baserunner from the second on.

"The first inning, I missed two pitches ... and after that ... I just made sure they didn't get anymore," Maholm said. "I was mixing speeds and mixing pitches and just let the defense do some work."

Maholm beat the Nationals for the first time in eight career starts and tied Zach Duke as PNC Park's all-time wins leader with 31.

Evan Meek worked a perfect eighth, and Joel Hanrahan struck out pinch-hitter Rick Ankiel looking with runners on first and third and two outs in the ninth to finish his sixth save.

Making his 100th career start, Lannan allowed only one hit before a one-out walk to Jose Tabata in the fourth. With two outs and Tabata at second, Neil Walker singled to right.

On Sunday, Jayson Werth threw Andrew McCutchen out at the plate to end the game, but his throw home this time was up the third base line and got past catcher Wilson Ramos.

That would be the last ball put in play before the delay. Washington had three postponements in a seven-day span last week.

"There's nothing you can do about that," Riggleman said. "It's Maryland and Pennsylvania in April. You're going to get that. We've dealt with it before and we may not be past it yet. We may get some more of it. It's just a situation you have to deal with."

Wood's double was the second hard-hit ball to right-center of the game. The first was caught on the run by Werth in the second inning, but this one one-hopped the wall.

Lannan was charged with four runs on five hits and two walks with three strikeouts in 5 2-3 innings. He had a five-game road winning streak snapped. The Nationals had won Lannan's past six road outings since last season.

The second-worst hitting team in the majors, Washington had only five hits a day after breaking out with a season-high 15.

"I know the players are a little frustrated with the hitting," Riggleman said. "I know I'm repeating myself, but we've got to win the ballgame anyway. We can't only win when we hit."

Notes: Washington had two errors to make it eight in the series after having only 12 over the first 18 games. ... SS Brian Bixler made his Nationals debut, going 0 for 3. ... Walker had two hits to give him five in his past two games. ... LaRoche has reached base in 17 of 19 games this season.