LOS ANGELES -- Tanner Roark had turned in one of his finest pitching performances of the season, but a single pitch spoiled the entire outing.

With two on and none out in the eighth inning, Yasmani Grandal hit a towering three-run homer to help the Dodgers come from behind to defeat the Washington Nationals 3-2 on Tuesday at Dodger Stadium.

"(Roark) obviously did a really good job today, especially keeping us off the bases and making pitches," Grandal said. "I was trying to figure out a way to get the ball in the air. Especially in that situation, you don't want to hit the ball on the ground, and obviously he was thinking the same thing."

Roark was, in fact, thinking the same thing.

"I tried to make a pitch inside to Grandal to get a double play," Roark said. "I just left it up."

Roark (6-5), who had been masterful all night behind a 2-0 lead, put the first two batters on in the eighth inning and Grandal drove the 2-1 fastball over the center-field fence. It was the catcher's sixth home run of the season.

Grandal had been just 3-for-25 before that at-bat but said he had seen signs of an improved swing in recent days. That key hit gave him tangible evidence.

"I feel like this whole month I've been hitting the ball pretty well, I just haven't been able to get it in the air," Grandal said. "When I look up and I see the ball going over somebody and going 100 miles an hour, that's all I'm trying to do -- I'm just trying to hit the ball hard. So far, I feel like I've been doing a pretty good job of that."

One day after becoming the Dodgers' all-time saves leader, Kenley Jansen earned his 21st save of the season with a perfect inning of relief.

Louis Coleman (1-1) recorded the win with one scoreless inning.

The victory was the Dodgers' fifth in a row and gave them the series win. Los Angeles has now homered in 12 straight games dating back to June 10, a season-high streak and the longest such streak for the club since May 23-June 4, 2002.

The Nationals have dropped four in a row for the first time all season.

Roark cruised through the first seven innings but took his first loss since May 20. He went 7 1/3 innings, giving up three runs on six hits, walking one and striking out five.

Scott Kazmir made few mistakes but a pair of solo home runs by the Nationals appeared as though they would earn him his first loss since May 20. Kazmir went five innings, giving up two runs on eight hits, walking one (intentional) and striking out four.

"I just had to battle out there," Kazmir said. "A couple 0-2 pitches that I wanted back but besides that, I was able to be a lot more consistent that I had in the last couple starts."

Danny Espinosa gave Washington a 2-0 lead when he led off the fifth inning with a solo home run, his 12th of the season.

Kazmir continued to pitch himself into trouble in the fifth, intentionally walking Daniel Murphy to load the bases with two outs. But he got Ryan Zimmerman to swing and miss on a curveball for strike three to get out of the jam.

The Nationals hit five doubles but left 13 stranded.

"We didn't hit with runners in scoring position," Nationals manager Dusty Baker said. "This is what we've got to get better at."

With two outs in the first inning, Bryce Harper drove a 2-1 fastball into the left-field stands to put the Nationals on the board. It was Harper's 15th home run of the season and just his second this month.

NOTES: The Dodgers reinstated RF Yasiel Puig (strained left hamstring) from the 15-day disabled list. He went 5-for-12 (.417) with a homer, three walks, one steal and two RBIs in five rehab games with Class A Rancho Cucamonga. To make room on the roster, the Dodgers optioned RHP Carlos Frias to Triple-A Oklahoma City. Frias was recalled Sunday and did not appear in a game. ... Dodgers manager Dave Roberts announced that 19-year-old RHP Julio Urias will get two more starts before the organization decides how to use to him the rest of the season. The club is trying to take into account his youth, but Roberts said they like his progression. Urias is scheduled to pitch the series finale against the Washington Nationals on Wednesday and will then make a start on the road against the Milwaukee Brewers. The soonest they will need to add a fifth starter is June 28 at Milwaukee. ... RHP Brandon McCarthy (Tommy John surgery) is scheduled to pitch four innings for Triple-A Oklahoma City, continuing his rehab assignment. ... LHP Hyun-Jin Ryu (left shoulder surgery) will make his next rehab start with Oklahoma City. He is scheduled to pitch five innings on Thursday. ... OF Ben Revere returned to the Nationals lineup and hit leadoff on Tuesday. Manager Dusty Baker had previously said OF Michael Taylor would start against left-handed pitching but didn't want Revere to get rusty. The Dodgers are starting three straight lefties in the series. ... The Nationals didn't have any updates on RHP Stephen Strasburg, who was scratched prior to his Monday start with an upper-back strain.