WASHINGTON — Eury Pérez’s walk problem finally caught up with the Miami Marlins on Friday night, as the 23-year-old right-hander threw 41 of his 74 pitches in a disastrous five-run third inning that sank the Marlins deeper into the National League Wild Card hole.

The loss — Miami’s first to Washington in nine games — dropped the Marlins to 68-67, four games behind the Padres for the final NL Wild Card spot and three behind the Diamondbacks with 27 games remaining.

“I think [Pérez] had some walks in some previous starts coming into this, and was able to navigate around those and not give up runs,” manager Clayton McCullough said. “And tonight, [he] just wasn’t able to do that.”

Pérez struck out five and allowed only two hits, but four walks and a wild pitch unraveled his outing. Entering Friday, he had pitched to a 1.80 ERA in 11 previous starts, though he had issued three or more walks in four of those outings. The command issues finally proved costly when Brady House hammered a sinker into the picnic-porch seating in left-center field for a three-run homer that blew the game open.

“It was a long inning, fatigue levels were high,” Pérez said through an interpreter. “I was trying to stay in the game in that inning, looking for somehow a pause, so I can take a breather. … It was hard. After that, the manager took me out of the game, and he had all the reasons to do that.”

The trouble compounded after Pérez appeared to escape the inning. He struck out Abimelec Ortiz on three pitches and benefited from an ABS challenge that turned a full count into a called third strike on Dylan Crews. But a wild pitch and a throwing error by catcher Joe Mack allowed two runs to score before House’s homer. Pérez absorbed a collision at home plate from Andrés Chaparro’s slide and stayed in the game after a visit from medical staff, only to walk Daylen Lile before House connected.

“I was confident that I was going to be able to get out of the inning,” Pérez said through an interpreter. “Pitching from the windup position, I think I feel a little bit better. Then the wild pitch happened, and I had to throw from the stretch. And it made it a little more difficult for me to finish the inning there.”

Xavier Edwards singled in Miami’s only run in seven innings off Nationals rookie starter Jackson Kent. “I think he kept us off the barrel,” McCullough said. “A lot of ground balls, a lot of weak contact. How he used the changeup and really mixed all of his stuff in. So, just all around, not a great night for us.”

Heriberto Hernández clubbed his 21st home run — and third in six games — off reliever Max Kranick in the eighth inning, but Washington had already tacked on four more runs in the seventh against Patrick Monteverde.

“I think there’s only so long in this league where you can dance around that number of free passes,” McCullough said. “The stuff at times to be able to get himself out of some of those jams. And he almost did tonight, but you put yourself in that spot often enough and it’s going to come back to bite you.”

The Marlins continue their series in Washington with 27 games left to close a four-game gap on San Diego for the final playoff berth.