Jason Marquis delivers during the seventh inning of his win over the Marlins. He improved to 5-1. (John McDonnell/THE WASHINGTON POST)

The Washington Nationals scored more runs in the first inning on Sunday against the Florida Marlins than in any of their previous three games overall. That early production, often absent during the first quarter of this season, roused an 8-4 victory that included another tenacious outing from starter Jason Marquis and some nifty defense in the late innings to help avert a sweep against a division rival.

In ending a three-game slide, the Nationals scored their most runs in nearly a month, collected 11 hits and had all but one player reach base on a picturesque afternoon before 18,356 at Nationals Park. Catcher Ivan Rodriguez led the barrage with three RBI, and Marquis had a pair of RBI and two hits to increase his batting average to .333.

Regarded as among the most reliable hitting pitchers in the game, Marquis also won for the fifth time in six starts by surrendering two earned runs on six hits and one walk in 62 / 3 innings. The bullpen did the rest, yielding one hit for the balance of the game.

“Jason pitched well, kept us in there, fought out of a few scrapes there and did a great job,” Manager Jim Riggleman said. “Getting the runs early was big. That’s been a little bit of an issue for us, and to get some early really kind of helped us out with some breathing room later.”

The Nationals (19-21) had slumping Florida starter Javier Vazquez at a deficit almost immediately, batting around in the first inning and scoring six times. The outburst began when leadoff hitter Roger Bernadina bunted for a single and moved to second on right fielder Jayson Werth’s one-out single. Bernadina was able to advance only because he was running on the pitch, or else shortstop Hanley Ramirez would have had a chance for a routine force out.

Werth instead beat the throw to first, and one batter later, Laynce Nix singled to left to score Bernadina for the first run. Werth had advanced to third on the hit, and when left fielder Logan Morrison’s throw to the base was off target, Nix wound up at second.

First baseman Adam LaRoche walked for the 23rd time, the most on the Nationals, to load the bases, and Rodriguez fought off several pitches before he flared a single into shallow right that scored two. LaRoche came home when third baseman Jerry Hairston grounded to short for a force out of Rodriguez at second.

Alex Cora, filling in at shortstop for an ailing Ian Desmond (strained left quadriceps), singled to right, and with runners on first and second, Marquis lined a bases-clearing double to left for his second and third RBI this season. Marquis tried to stretch it into his first triple in five seasons, but he was unable to beat the tag while sliding into the bag.

The Marlins got two back in the second, beginning when first baseman Gaby Sanchez led off by reaching safely on Hairston’s throwing error that pulled LaRoche off the base. Sanchez got to third on Morrison’s double in the next at-bat and scored on right fielder Mike Stanton’s sacrifice fly.

Morrison then came home courtesy of catcher Brett Hayes’s two-out single to left. Neither of Florida’s runs was charged to Marquis, who got out of the inning by fielding Vazquez’s soft comebacker and tossing to first.

The Nationals recouped one of those runs in the fifth inning, which began with a leadoff single by Werth. The $126 million free agent acquisition was running on reliever Brian Sanches’s 1-2 forkball, and it was a good thing because otherwise Werth may have been the first out of a double play on Nix’s grounder to second.

Werth was safe, though, and he came home via Rodriguez’s two-out double for a 7-2 lead. Rodriguez advanced to third when Hairston singled one batter later, but Cora popped up to short to end the inning.

That was ample support for Marquis, who through six innings was working on his best outing of the season. Then trouble came calling in the seventh after Stanton led off with a double and scored on another double by Greg Dobbs to cut the lead to four. Marquis induced consecutive flyouts to center and appeared back in control until Chris Coghlan singled to left to make it 7-4.

Marquis’s afternoon was complete at that point, and Todd Coffey came sprinting to the mound. Coffey soon was gone too, lasting just one batter when he absorbed Emilio Bonifacio’s liner that caromed off his right arm and forced him from the game. Tyler Clippard got the final out of the inning, and although he permitted two base runners in the eighth, the setup reliever escaped without damage thanks in large part to LaRoche’s catch on hard liner and subsequent tag of Sanchez for an unassisted double play.

The Nationals tacked on their final run in the eighth on Bernadina’s infield single that allowed Rodriguez to score from third. Then in his second day in the majors, reliever Cole Kimball finished off Florida by getting three straight outs after a leadoff walk in the ninth.

“You get rewarded with wins when you throw the ball well,” said Marquis, who improved to 5-1 with a 3.54 ERA. “Sometimes you throw the ball well, and it’s not the outcome you want. That’s baseball. Things even out. I’ve had a lot of those over my career. Hopefully I can stay away from that this year.”