WASHINGTON -- Right-hander Josh Johnson dominated the Nationals for seven innings, but the game of baseball goes nine frames. The Nationals came back from a four-run deficit to beat the Marlins, 6-4, at Nationals Park on Tuesday night.

After giving up a single to Josh Willingham in the first inning, Johnson retired 20 straight batters before Willie Harris singled to right field in the bottom of the eighth.

"That's the best I've seen in a long time," Nationals outfielder Adam Dunn said about Johnson. "We knew he is the best righty in the game. He was unhittable."

But things started to turn in a positive way for Washington in that eighth inning.

Alberto Gonzalez and Wil Nieves had back-to-back singles to load the bases. Ronnie Belliard pinch-hit for Ron Villone, and the move by interim manager Jim Riggleman paid off. Belliard doubled over the head of Florida left fielder Chris Coghlan to drive in Harris and Gonzalez.

"I think you have to give Ronnie Belliard a lot of credit," said Marlins catcher John Baker. "I know he's having a tough year and he's struggled, but he's always a threat because he's a professional; he's been around so long. He over-swung on a 2-1 slider, and J.J. didn't make quite the same pitch he did before. It was up just enough, and he made a great adjustment."

Under Riggleman, Belliard is swinging the bat a lot better. He is hitting .276, as opposed to having a .184 average in the first half of the season.

"I think he has a little more giddy-up in his walk," Riggleman said. "He is getting after it. I think he's feeling like, 'Let's go. If this is my role, I'm going to accept it and get after it.' I'm going to try to get him in there a little more because he is such a good hitter."

Johnson left the game in favor of left-hander Renyel Pinto, who got Nyjer Morgan to ground out, but Nieves scored on the play.

Right-hander Kiko Calero entered the game for Florida, and he gave up a game-tying RBI single to Cristian Guzman.

Two batters later, lefty Dan Meyer was on the mound to face Dunn with two outs. On a 3-2 pitch, Dunn, who struck out three times before the at-bat, hit the ball over the left-field wall to give Washington a 6-4 lead.

"He threw me a fastball. I wasn't sure what was coming," Dunn said. "Meyer has a good slider-cutter thing. He has a good heater, so you have to respect his heater."

A month ago, the Nationals would not have won a game like the one on Tuesday. There would have been a good chance the bullpen would have imploded and the offense would have had a tough time hitting with runners in scoring position.

Asked why things have turned around, Riggleman said, "The ballclub is feeling pretty good about itself. There are a lot of veterans in there. It's perceived as a young club. It's a young pitching staff, but there are a lot of veterans in there with a lot of pride.

"Josh Bard and Wil Nieves take a lot of pride at what they do behind the plate. Dunn, Willingham, Nyjer, who is not a kid -- there are a lot of guys who want to turn this thing around and be part of it. I'm trying to go out there with them."

Nationals rookie right-hander J.D. Martin struggled, lasting 4 1/3 innings and giving up three runs on six hits.

Florida took a 1-0 lead in the first inning, when Nick Johnson singled under the glove of Dunn at first base to score Coghlan.

Three innings later, Cody Ross and Josh Johnson hit solo home runs. With Villone on the mound in the seventh inning, Jeremy Hermida drove in Nick Johnson with a single to right. The run was charged to Jason Bergmann.

The good thing was Bergmann and Villone were able prevent any additional damage.

"They really have done a great job," Riggleman said of the bullpen. "I can't say enough about Villone. He has been just a horse for us in terms of taking the ball, giving us multiple innings and getting up every day. You know he has been around a long time. He has been a manager's dream as far as picking innings up and getting big outs."

The Nationals have won seven out of their past 10 games and improved their record to 35-72.