Ryan Zimmerman celebrates moments after his three-run homer cleared the wall in left field in the bottom of the eighth inning. (John McDonnell/The Wahington Post)

The tension, already bordering on a code-red panic, emanated through Nationals Park on Saturday night, intensifying the longer the home club’s offense stayed quiet. It threatened to seep into the Washington Nationals dugout as chances dwindled and frustration grew.

But a quiet confidence remained among the men in uniform as they entered the eighth inning with two hits on the night and four in the series. Gio Gonzalez and the bullpen had kept them close. All they needed was that one hit.

Bryce Harper, their 24-year-old showstopper provided it, blasting that anxiety into oblivion with an upper-deck, game-tying home run. Three batters later, Ryan Zimmerman discarded his ugly history against the Cubs with a three-run go-ahead home run into the flower bed just beyond the wall, the decisive blow in a 6-3 victory to tie the National League Division Series at one.

“I just knew in the bottom of my heart that we were going to explode for some numbers,” Nationals Manager Dusty Baker said, “which we’ve done all year.”

For 7½ innings, Game 2 resembled Game 1 in nearly every way but one: The Nationals scored a run. Anthony Rendon provided the offense in the first inning with a solo home run off left-hander Jon Lester that carried to the Nationals’ bullpen beyond the wall in right field. Rendon had hit just two of his 25 homers during the regular season the other way.

Lester then retired the next nine batters he faced. He yielded one other hit, walked two and held Washington scoreless over the next five innings. The Nationals hoped to wreak havoc on the base paths on Lester, notorious for his inability to throw to bases. But they couldn’t get guys on base.

Gonzalez wasn’t as dominant as Stephen Strasburg was in the opener, but he did not fail to keep the Nationals within striking distance. Making his first postseason start at home since 2012 because Max Scherzer’s tight right hamstring delayed his playoff debut, the left-hander allowed three runs on three hits — one a solo home run by Willson Contreras — in five innings. He struck out six, walked two and threw 83 pitches before giving way to the bullpen.

Matt Albers, Sammy Solis, Ryan Madson and Oliver Perez pieced together the bridge to the bottom of the eighth inning.

The abrupt five-run salvo began with Adam Lind, pinch-hitting in the pitcher’s spot, smacking a single to left field off Carl Edwards Jr. in his first career postseason at-bat. Victor Robles then entered the game to pinch-run for Lind before Trea Turner struck out to bring up Harper.

Before playing in his seventh game back from a 42-game stint on the disabled list, Harper matter-of-factly stated that there was room for improvement to return to his pre-injury level. That improvement didn’t surface in his first three plate appearances; he stepped to the plate in the eighth inning 0 for 3 with a couple groundouts and a strikeout. He looked overmatched again on the first pitch from Edwards, swinging at a wicked curveball in the dirt.

The right-hander then went with three straight fastballs — 96, 94, 95 mph — out of the strike zone, and Harper didn’t bite. The sequence altered the course of the at-bat — and the Nationals’ season. With the count 3-1 and a runner on first base, Harper assumed Edwards wouldn’t throw a ball in the zone.

“I thought about taking the whole way,” he said.

But those plans changed when he recognized the loop in Edwards’s 80 mph curveball. The detection incited the former MVP’s instincts, and he turned on the pitch, depositing it 421 feet away, deep into the second deck.

He admired his work as he flipped his bat and started his trot, the top of his jersey unbuttoned and flopping with each pace as the ballpark’s decibel levels reached rare heights.

“Sometimes it takes kind of just one hit for everyone to exhale,” Zimmerman said. “Everyone who has played baseball has been there before. Baseball is contagious.”

The momentum change continued. Rendon walked, which prompted the Cubs to replace Edwards with lefty Mike Montgomery, to face Daniel Murphy, a left-handed hitter. Murphy lashed a single anyway, leaving a favorable matchup for Zimmerman. After taking a strike, Zimmerman pounced on a change-up over the plate, lifting it high into the balmy air with the wind blowing out. He watched, slowly jogging to first base, unsure if he had gotten enough, as it carried and carried and carried just over the wall in left field.

The ballpark erupted again. Harper jumped out of the dugout in glee.

“Great launch angle,” Harper noted.

The Nationals didn’t exorcise any postseason demons, if there are any, on Saturday. They are two wins from that, from breaking through the NLDS barrier and advancing to the first National League Championship Series in franchise history. The chances of another one-and-done playoff run remain.

But, for one night, the dread was forgotten. Game 3 — and Scherzer — await Monday at Wrigley Field.

“The train’s coming,” Harper said. “We’re a great team.”