WASHINGTON -- Slowly, some momentum is building.

Behind Mike Stanton's two-run homer and Ricky Nolasco's six shutout innings, the Marlins defeated the Nationals, 5-0, on Thursday in front of 16,496 -- who withstood a nearly two-hour rain delay at Nationals Park.

By completing their first three-game series sweep of the season, the Marlins also matched their season-best four-game winning streak.

Now 57-56, they are over .500 and showing overall improvement as their 10-game road swing heads to Cincinnati on Friday.

"This is big. We came out and we've been swinging the bats," Nolasco said. "We've got to tip our caps to the hitters this series. They've been swinging the bats, and made our jobs a little easier. Pitching with the lead changes the whole game. The pitchers have to tip our caps to the hitters."

The Marlins outscored the Nationals 22-7 in the series.

Nolasco (13-8) struck out eight and allowed six hits, as he won for the eighth time in his last 10 decisions.

Livan Hernandez, who has beaten the Marlins 13 times in his career, now has lost twice to Florida this year. The veteran, who was the Marlins' World Series MVP in 1997, gave up three runs in 6 1/3 innings.

Nolasco was able to rebound from a tough outing against the Cardinals, a loss in which he allowed seven runs in five innings.

Florida's other four-game win streak came from May 13-16, against the Mets.

Nolasco, Jose Veras, Clay Hensley and Burke Badenhop combined on the Marlins' 11th shutout of the season.

Heavy rain delayed the start one hour and 57 minutes, but once play began weather was not a factor.

The way Nolasco was throwing, he didn't need much run support. Yet, he received an early boost by Stanton -- the 20-year-old phenom who keeps maturing.

After the lengthy delay, the Marlins once again struck early. Stanton's two-run homer in the second inning marked the third straight game in which Florida scored in either the first or second innings.

"I think that was the key for the series, for the starting pitchers," Marlins manager Edwin Rodriguez said. "Coming in and pitching with a lead is very important for the starting pitcher, giving him some room to work."

Dan Uggla walked to open the second. With one out, Stanton stepped in -- riding a string of five straight hits.

Hernandez threw a 1-0, 79 mph forkball to Stanton, who swatted it deep to right-center field. The ball sailed over the high wall, and bounced back onto the field.

Initially, the ruling was that the ball was in play. Uggla raced from first to home, scoring without a play. Stanton strolled into third, slipped on the bag, but remained on the base.

Not even Stanton was sure the ball was out.

"I don't know. It was right in-between," Stanton said. "I'm not really sure."

Rodriguez approached home plate umpire Mike Winters asking for an instant replay review. The umpires huddled, and then left the playing field to take a look at the technology. It didn't take long for them to return and signal the ball had left the ballpark.

During the review, Nationals third baseman Ryan Zimmerman told Stanton he thought the ball was out.

"Zim said he thought it was out. I can't really tell running the bases," Stanton said. "When the umpire walked to their manager that's when I knew. I fell on my butt a little bit."

Rodriguez said he felt the ball was out more on sound than sight.

"I heard something, I have to say that," the Marlins manager said. "It was a different sound. Like it hit something up there. I was relying more on what I heard than what I saw."

The home run was Stanton's 12th in his 53rd MLB game since being promoted from Double-A Jacksonville on June 8.

On Wednesday, Stanton matched a Marlins record with five hits. The 20-year-old was a triple shy of the first cycle in franchise history.

The amazing thing about Stanton is he was playing the last two days with a sore throat.

"I have a really sore throat. I didn't sleep really well last night," the rookie said. "Then I got soaked this morning going to the store."

A two-out RBI single by Cody Ross in the third inning made it 3-0. Logan Morrison, who singled with one out, scored his fifth run of the series.

Nolasco was able to wiggle out of some rough patches. In the fifth inning, the right-hander issued a leadoff infield single to Ivan Rodriguez and a walk to Willie Harris.

With two outs, and runners on the corners, Nolasco hit Ian Desmond with a pitch, filling the bases. But, the threat ended when Adam Dunn swung through an 84 mph slider to strike out.

Through five innings, the Nationals were 0-for-8 with runners in scoring position off Nolasco.

Nolasco came out for the seventh inning, but ran into trouble when Rodriguez and Harris each singled. After 106 pitches, the right-hander was replaced by Jose Veras in a three-run game.

Veras fell behind 2-0 to Alberto Gonzalez, but came back to induce a 6-4-3 double play. With Rodriguez on third and two outs, Veras retired Roger Bernadina on a routine fly ball to left.

In the eighth inning, the Marlins added an insurance run when Uggla, who singled, scored on Craig Stammen's wild pitch. Uggla added an RBI single in the ninth inning.

The Marlins travel to Cincinnati hoping to get back into the playoff picture.

"We've just got to take it one game at a time, that's all we can worry about," Nolasco said. "We know what's at stake here. We're just trying to be consistent, and not get ahead of ourselves. If we can put some things together, then we can start talking about some other stuff."