WASHINGTON -- This has been an uneven spring for Tanner Roark, the right-handed starter for the Washington Nationals.

He pitched for the U.S. team in the World Baseball Classic, but that messed up his regularly spring training preparation.

Roark also had to adjust to new catcher Matt Wieters, but that seems to be working out after he gave up two runs in six innings as the Nationals beat the Miami Marlins 6-4 on Wednesday. The tandem worked together only once in spring training.

"It is encouraging to have that kind of faith in your catcher," Roark said. "It builds your confidence out there. It was our second time working together. I like the way he calls a game."

Wieters is also adjusting when he is at the plate as he went 3-for-3 with a walk and drove in two runs as the No. 8 hitter. Bryce Harper had two hits and drove in two runs and Jayson Werth and Daniel Murphy also had two hits.

"We have a good group of hitters," said Washington first baseman Ryan Zimmerman, who homered and scored two runs. "Professional hitters who grind out at-bats. One through eight is not easy for the other side. We feed off each other as well."

Zimmerman is hitting .429 early after a career-worst mark of .218 last season.

"I feel good, obviously. The last few years have been frustrating," he said.

It was a frustrating night for Marlins manager Don Mattingly, who was ejected in the top of the seventh after the third Marlins hitter of the night -- Derek Dietrich -- was hit by a pitch.

Dietrich, was hit by a pitch on the first offering from Washington reliever Enny Romero. Dietrich shouted at Romero as he went to first and Mattingly had words with home plate umpire Ron Kulpa, who quickly tossed him.

"We got hit three times (in the game) and we got a warning," Mattingly said. "I didn't quite understand that. Dietrich has been hit three times in two games."

Roark (1-0) won 16 games last season and began this year by allowing two runs in the first before bouncing back. He gave up two runs, two walks, two hit by pitches and a wild pitch before being lifted for a pinch-hitter in the sixth.

J.T. Realmuto hit a solo homer off Romero in the eighth to trim the lead to 6-3. Dietrich grounded out against Oliver Perez to end the inning with two runners on base. Blake Treinen pitched the ninth for his second save but not before Realmuto drove in a run to make it 6-4 with his second hit.

The losing pitcher was Dan Straily (0-1), who gave up five earned runs in 3 1/3 innings. Christian Yelich and Marcell Ozuna had two hits for the Marlins but Yelich fanned for the last out in the ninth.

Ozuna stroked a two-run single with the bases loaded and two outs in the first to give the Marlins a 2-0 lead.

Zimmerman hit a solo homer to right with one out in the second to pull the Nationals to within 2-1.

Washington scored four times in the fourth to take a 5-2 lead.

Harper recorded an RBI double, Murphy added an RBI single and Wieters drove in two runs with a single through the left side to chase Straily, who was victimized when a bloop single off the bat of Werth fell between center fielder Yelich and second baseman Dee Gordon before Wieters followed with a ground single with one out.

"We didn't play well enough to win," Mattingly said. "We gave them extra outs. We just made too many mistakes. There were outs we were given that we should have taken."

Harper tacked on an RBI single in the fifth to build the margin to 6-2.

Roark won 15 games as a starter in 2014 then spent most of 2015 in the bullpen.

"I gave 97 (pitches). I didn't feel like I threw 97 so that is a good sign," Roark said. "I was maybe thinking too much out there and threw too many pitches (early on). After that second inning I got my mindset right and went out there and attacked."

NOTES: Washington 3B Anthony Rendon, who has been dealing with a sore calf, was in the starting lineup after he did not play Opening Day. He hit sixth in the order and was 0-for-4. ... Marlins 3B Martin Prado is on the disabled list with a left oblique strain and could play the middle of this month, manager Don Mattingly said. Prado hit .305 last year with 75 RBIs. "All the things are progressing," Mattingly said. ... There was a moment of silence for former Washington Senators outfielder Roy Sievers, who died Monday at the age of 90.