With six home runs and 13 RBI in four games, Bryce Harper is one of the most dangerous hitters in baseball. Post Sports Live discusses why Harper is finally playing up to his potential. (Post Sports Live/The Washington Post)

Chocolate sauce dripped down Ryan Zimmerman’s face late Tuesday night, smeared over a subdued grin. His home run off the right field foul pole a few moments before gave the Nationals an 8-6 win over the Yankees, a rally from a four-run deficit to a fourth straight victory. For the first time in his career, stoic, steady Zimmerman was drenched in Gatorade and water and topped with chocolate. For the first time all season, the Nationals had a share of first place in the National League East.

“That was a pretty aggressive celebration,” said Zimmerman, who has plenty to compare it to. Tuesday’s was the 10th walk-off home run of his career.

Given the way the Nationals pinballed through the first quarter of the season, ricocheting off injuries and spinning through offensive struggles, it was only fitting they moved atop the division with an up-and-down game like Tuesday’s.

The Nationals (23-17) have won 16 of their past 20 and are tied for first with the Mets, who lost Tuesday.

The Nationals are finally improving on their below .500 start to the season. Post Sports Live debates whether the team is playing up to its potential. (Post Sports Live/The Washington Post)

The Nationals led 2-0 Tuesday night. Then they trailed 6-2. They homered three times but came up empty in key situations with men on base. They made big defensive plays to back five scoreless innings from the bullpen. And they finally got a clutch hit they needed against Andrew Miller, a pitcher who had allowed just three hits to the 70 batters he faced before Zimmerman stepped in with one out in 10th.

Zimmerman let Miller’s brutal sliders go and smashed a fastball to right for another walk-off home run. Miller hadn’t given up an earned run all season before the blast.

“Pretty special isn’t it?,” Nationals Manager Matt Williams said of Zimmerman’s propensity to end games in that way. “You don’t realize things like that until it’s pointed out. It just means that he knows what he’s doing. He hits to the situation like he did tonight. He got ahead in the count and got a good pitch to hit. He’s got power to all fields, we know that. And tonight he hit the foul pole.”

The Nationals’ bullpen outdueled the formidable Yankees pair of Miller and Dellin Betances, who threw a pair of hitless innings.

An extra-inning slugfest seemed improbable through the first three innings, as Gio Gonzalez induced groundouts to the first nine batters he faced, working quickly and efficiently.

Normally, Gonzalez strikes out batters and gets flyballs, but he is prone to losing control. In the fourth inning, Gonzalez’s command dissipated again, and he did not last past the fifth. He threw 30 pitches and was perfect through three innings, after which he led 2-0; he threw 45 pitches in the next two, after which he trailed 6-2.

The Nationals rallied in the bottom of the fifth with four straight hits from pinch hitter Clint Robinson, Denard Span, Yunel Escobar and Ian Desmond. An inning later, Wilson Ramos completed the comeback with a home run to left that extended his hitting streak to a league-best 19.

The next inning rookie Wilmer Difo, who was called up from Class AA Harrisburg on Tuesday, pinch-hit for Blake Treinen. He swung at the first two pitches of his major league career. He hit the second up the middle for a single but was stranded there.

So the game fell to the bullpens, and with Betances and Miller, the Yankees looked better positioned to win such a duel. They did not, because Treinen, Matt Thornton, Aaron Barrett, Drew Storen and Matt Grace — the eventual winner — combined to hold the Yankees down.

“It’s big for us,” Storen said. “Especially in a big game like this, to have guys come out of the pen and come up in big spots and just give us an opportunity to win late in the game is all that we’re asked to do.”

That set up Zimmerman, whose blast helped put the Nationals’ April struggles firmly behind them.

“He’s not a real emotional guy,” Storen said. “He just doesn’t get caught up in the moment and try to do too much. So he just goes up there and has a professional at-bat, no matter what. Obviously, more times than not, it works out pretty well for him. It’s a lot of fun to watch.”

On April 27, the Nationals were six games under .500 and in last place in the NL East. They are now tied for first, winning so often and so dramatically that they’ve coined a celebration, one that left even even-keeled Zimmerman grinning from beneath the chocolate.