Cody Ross got things rolling with a home run to open the first, Dan Uggla connected on his first career grand slam and Wes Helms also went deep.

With plenty of support, Andrew Miller cruised along to his third straight decision and the Marlins claimed an 11-0 victory over the Nationals on Saturday night.

Riding a season-high six-game winning streak, the Marlins have improved to 7-1 against Washington on the season. The combined shutout was Florida's third of the season.

Now 22-14, the Marlins improved on their best start through 36 games and are 10-5 on the road. Saturday also marked their largest margin of victory this season, topping a seven-run gap over the Padres on May 4. The 11 runs are a season high.

"Cody, we've seen him do that off left-handed pitching, and that's why we wanted to see him get some at-bats," manager Fredi Gonzalez said. "We swung the bats well. But I thought the name of the game today was Miller. He was good. He was sharp, and he gave us seven innings."

In just his third game and ninth total at-bat hitting in the leadoff spot, Ross gave the Marlins an immediate advantage, ripping Mike O'Connor's first pitch over the left-field wall. It was Florida's fourth leadoff homer of the season, with the other three coming from Hanley Ramirez.

The Marlins are platooning their leadoff spot between Ross, against left-handers and some righties, and Alfredo Amezaga. Ramirez had the knack of starting things off with a home run before the lineup switch was made on May 2.

"I told Hanley before the game that I was going to try to do what he does, hit the first pitch," Ross said. "I got a good pitch to hit, and got some good wood on it."

When he returned to the dugout, Ross said to Ramirez, "I told you so."

The Marlins used a seven-run fourth inning to break it open. Helms homered to open the inning, and after O'Connor was replaced by Joel Hanrahan, Uggla smacked a grand slam to left. It was Florida's second grand slam of the season, with the other coming off the bat of Mike Jacobs on April 5, against Pittsburgh.

Thanks to this impressive run, the confidence in the clubhouse keeps growing.

"I think we're pretty good," Miller said. "I think all the guys in here think we're pretty good. I think we're pretty balanced, especially if the starting pitching keeps it up.

"Obviously, I pitched pretty poorly in the beginning of the year. Our bullpen has been great, and our offense has been phenomenal. Those are three keys right there, so I don't know why people would expect less of us."

With the game out of hand, Luis Gonzalez doubled in the seventh inning. It was the 575th double of his career, putting him in sole possession of 18th place all-time.

The big offensive output further put Miller (3-2) in a comfort zone. The left-hander tossed a season-high seven innings, yielding two hits while striking out seven. He threw a season-high 103 pitches.

It was another big step for Miller, who matched his career high in strikeouts. The lefty got into a bit of trouble in the first inning when he allowed a one-out single to Cristian Guzman, and with two outs, Nick Johnson walked. But the inning ended when Ramirez robbed Lastings Milledge of a single with a nice lunging catch.

From that point, Miller rolled along and got through seven innings for the first time since July 23, 2007, when he was with the Tigers. His longest outing before Saturday was six innings, which came in his last start -- a win over the Padres.

The changeup was a big pitch for Miller, and it's one that he hadn't thrown for much success or as often until this season.

"With the way [things] went, and the offense getting us all those runs in the beginning, you want to go out there and get seven innings, at least," he said. "If I hadn't been so poor getting the ball over the plate on the first or second pitch, I probably could have gotten another [inning].

"But the point is working deep into games. We know we're going to get a lot of runs the way our games have been going."