In his first game back from resting his inflamed right shoulder, third baseman Ryan Zimmerman sparked the Nationals’ comeback with a sixth-inning double. (Ricky Carioti/The Washington Post)

An eventful Wednesday evening at Nationals Park had come to this: Jayson Werth at the plate with one out in the eighth inning, the bases loaded and the Miami Marlins clinging to a one-run lead over Washington with reliever Carlos Marmol on the mound.

By now, Jordan Zimmermann’s clunker of a start, the shortest of his career, seemed a distant memory. So was Bryce Harper’s three-run home run into the third deck of right field, along with Craig Stammen’s powerhouse 31 / 3 innings of relief and the late-game stumbles from relievers Drew Storen and Tyler Clippard.

In a back-and-forth game, with leads lost and gained, it was Werth who struck the game’s defining blow. He drilled Marmol’s 94 mph fastball into the visitor’s bullpen in left field. The grand slam earned Werth a curtain call from the chilly souls who remained late into the evening. A few minutes later, closer Rafael Soriano collected three outs in the ninth to seal the 10-7 win with his second save.

“When you’re put in that situation and the game is on the line, you want to come through for your teammates,” Werth said. “I was happy to do that.”

In the season’s first eight games, the Nationals already have four comeback wins, a trait that was often absent from last year’s team. The Nationals rallied from deficits of 5-0 and 7-6 on Wednesday.

The Post Sports Live crew discusses the most concerning of the Nationals’ myriad early-season struggles – from Harper’s slow start to Zimmerman’s throwing woes and injury concerns. (Post Sports Live/The Washington Post)

“If you look at the way we played down the stretch in the second half and the way we play so far this year, I think that can become an identity for sure,” Werth said. “We just have to keep going and keep pressing. Take opportunities when they’re given to us and keep winning ballgames.”

After Zimmermann failed to get out of the second inning with Washington in a 5-0 hole, the Nationals clawed back — sparked by Harper’s three-run home run off left-hander Brad Hand.

The Nationals took a 6-5 lead in the sixth thanks to the hitting of Ryan Zimmerman, speed of Ian Desmond and fielding gaffes by the Marlins. But after the runs allowed by Storen and Clippard, the Nationals needed another rally.

With one out in the eighth, Marmol hit pinch-hitter Nate McLouth in the leg. Then Denard Span bunted a ball down the line that third baseman Derek Dietrich fielded but fired wildly to first base. McLouth moved to third, Span to second. With first base open and the red-hot Anthony Rendon (two hits to that point, a .419 average) at the plate, Marlins Manager Mike Redmond opted to walk him and take his chances with Werth, who was hitless in his first four at-bats.

Werth insisted the intentional walk ahead of him didn’t bother him — “I wasn’t shocked” — and was angrier about the strike one call. But after he hit the next pitch over the fence, Werth threw the bat to the side and pointed to the dugout as he raced around first base.

“Knowing Jayson, if a pitcher looks at him wrong, he’ll take that personally,” Stammen said.

By that point, Zimmermann was long gone. His slider broke perhaps half the amount it normally does. His velocity was normal — he consistently hit 93 mph with his fastball — but he was missing badly with his pitches. Zimmermann allowed five hits in the second, including a two-run shot by Dietrich that hit the top of the wall in right field and was ruled a home run after a review. Manager Matt Williams finally took Zimmermann out of the game with two runners on and two out in the second inning.

“I felt good in the bullpen and I got out there and I just couldn’t locate,” Zimmermann said. “I have no answer for you. I wish I knew.”

The Nationals offense provided the runs to offset the pitching mistakes, starting in the fourth,when Harper snapped out of his slump. Harper entered Wednesday’s game hitting .160 (4 for 25) with 11 strikeouts. He had been mired in an early-season funk that prompted him to declare he was “lost” and felt “terrible” at the plate only four days before. Because a left-handed pitcher was starting, Williams inserted Harper into the starting in the seventh hole, the lowest the star outfielder has hit since the first four games of his major league career.

But with one vicious swing, Harper dispatched nearly two weeks of struggle.

“That’s a big swing for him, confidence wise,” Williams said. “It’s a big swing for us. It allowed us to get back in the game.”

A review of the home run by umpires only allowed the fans in the stands to watch a replay of the blast and drop their jaws. And with his grand slam in the eighth, Werth would send the Nationals to victory.

“It was a crazy game,” he said. “Back and forth. One of those games where you play that long you want to win.”