The Nationals were down, 3-2, in the bottom of the seventh inning when they took the lead off right-hander Jeff Fulchino. With Justin Maxwell on first and one out, Espinosa drove a 1-0 pitch over the right-field wall to give the Nationals the one-run lead.
"I thought the ball was going to hit off the wall. I had no thought that it was going out of the park," manager Jim Riggleman said. "I was hoping that it wasn't catchable. That's what he could do from both sides of the plate."
Even Espinosa wasn't sure if he had hit his fifth home run of the season.
"I wasn't sure [if it was a home run]. I knew I hit the ball well," he said. "I didn't know if it was high enough because the wall is so big. I knew at least I was going to get a double."
Espinosa had a simple solution of getting out of his slump: Focus on swinging at pitches down in the strike zone. During his slump, Espinosa was swinging at balls that were high and outside.
"I didn't do anything mechanically. I just have to see the ball down," Espinosa said. "I wasn't chasing anything under. It was higher. There was something I had to focus on. I talked to [hitting coach] Rick [Eckstein] and he thought it was a good idea that I lay off those types of pitches."
Reliever Tyler Clippard pitched two-thirds of an inning to pick up his team-leading 11th victory of the season despite allowing a two run-single to Angel Sanchez, who gave Houston a 3-2 lead in the top of the seventh.
"I didn't keep the score where I needed to be," Clippard said. "I definitely would have liked to get [Jason Marquis] a win and all that good stuff. It didn't work out that way. I tried to keep us in the game as much as I could. But we got a win, which is the most important thing."
As for Marquis, he made up for his last outing in a big way. He was solid for six-plus innings Wednesday, allowing two runs on seven hits after an effort Friday in which he allowed six runs to the Phillies over just one-third of an inning. While he was on the mound against the Astros, Marquis' only blemish was an RBI single to Jason Michaels.
"In Philly, I didn't get ahead of the hitters," Marquis said. "Tonight, I felt I pounded the strike zone a little more. I was consistent early in the count. I controlled the counts and was able to get some quick outs. The defense did a great job. It was definitely nice to get back-to-back wins."
There were times during the game when Riggleman felt Marquis was uncomfortable on the mound. He often got off the rubber as catcher Ivan Rodriguez went to talk to him. Marquis said he was just trying to clear his mind.
"Sometimes, you just don't feel right if it's a wrong pitch," Marquis said. "You think about the situation, what you want to do with the pitch. You step off the mound to slow the game down for yourself. Just get your bearings back, go out and make sure you are confident with what you want to do."
Both Espinosa and Marquis were able to get their confidence back, while the Nationals were able to improve their record to 64-88.