They had a Cy Young candidate on the mound, living history in center field and a rejuvenated set-up man in the bullpen. And yet, if you had to pick only one reason the Washington Nationals pushed closer to the National League East title Thursday night, it would not be Gio Gonzalez, Bryce Harper or Tyler Clippard.

For the past few weeks, Nationals Manager Davey Johnson has singled out Michael Morse as the only missing piece of a potent offense. Pain fired through Morse’s left wrist and his right hand, and one of their biggest sluggers had become a hole in the middle of their lineup. In time for the playoffs, it seems the Nationals can close the file on that problem.

In the Nationals’ 7-3 victory over the Phillies at Citizens Bank Park, Morse drove in four runs and crushed two homers. The second came in the sixth inning and soared some 451 feet, landing in the back bullpen in right-center field. Morse hopped after he finished his wicked swing and admired the flight of the ball, the blow that provided the separation the Nationals needed to lower their magic number to three with just six games remaining.

“I guess it’s never too late to get going,” Morse said. “I feel good. It’s been a tough year for me, but this team is doing so great that everybody’s been picking up everybody the whole year. I guess that’s what good teams do.”

Down in Atlanta, the Braves won their fifth straight, which meant the earliest the Nationals can clinch the East is Saturday night in St. Louis. But the Nationals know they can clinch if they handle their own business, which is what they did emphatically Thursday night.

Gonzalez, the Nationals’ No. 1 starter for the playoffs, turned suddenly from horrendous to splendid for his major league-best 21st win. Harper inched closer to another milestone with another home run. As a bonus, scuffling set-up man Clippard struck out two in a 1-2-3 eighth inning.

They give the Cy Young award for mastery, not mettle, and so Gonzalez may not have helped fill his trophy case Thursday night. But after he allowed three runs in the first, he refocused and finished his start with five scoreless innings, which left his ERA at 2.89.

“You have to bounce back,” Gonzalez said. “You want to show your team that you’re not going to lay over and take a beating.”

Harper had given Gonzalez a lead by drilling a home run in his first at-bat for the second consecutive night. He launched Tyler Cloyd’s 0-1 cutter into the right field seats. Harper’s 21st home run placed him three behind Tony Conigliaro’s total in 1964, the most a teenager has hit in a single season.

As Gonzalez settled on the mound, the Nationals chipped away at a 3-1 deficit. Morse crunched a solo homer in the second inning to the first row in left field, just his third home run since Aug. 18. Ryan Zimmerman laced a leadoff double in the fourth and scored on Morse’s groundout to tie it. Harper gave the Nationals the lead by flaring an RBI single in the fifth.

Morse finished Cloyd’s night in the sixth when annihilated a 2-1 changeup. The crowd gasped as the ball carried to right-center field. There was no doubt from the moment the ball left the trademark. Morse tossed his bat and took two slow steps. The last time a visiting player had sent a ball into the back bullpen came when Zimmerman did it 2009.

“That was one of the farthest balls I’ve seen hit,” catcher Kurt Suzuki said. “He’s just a threat.”

In the visitors’ bullpen, Tom Gorzelanny leapt off the bench and, incredibly, snagged the ball in his cap. He held it aloft as his fellow relievers celebrated as if they won the pennant. Afterward, they lobbied for him to make SportsCenter’s top plays.

“Good thing he caught it,” Clippard said. “If he missed it, that would’ve been pretty bad heckling for a few days.”

Impressive as the catch was, Morse’s night was the big takeaway. Two days ago, Johnson said, Morse began pulling the ball more in batting practice and feeling “frisky.” He received a battery of treatment Monday to relieve inflammation in his left wrist, and he has felt the back to his old self.

“It’s more stable,” Morse said. “I guess that’s the word I can say. Which makes it more, I guess, strong, back to normal. I don’t have to think about it, which is good. . . . This is perfect timing right now.

Morse’s blast given the Nationals enough breathing room to begin thinking about where Gonzalez may figure in the Cy Young race. Thursday afternoon, New York Mets knuckleballer R.A. Dickey bolstered his case with 13 strikeouts in a win, his 20th, over the Pittsburgh Pirates.

Gonzalez retired the first two batters he faced, two quick groundballs, and then, after Chase Utley rolled a single through the right side, he suddenly unraveled. “Gio about gave me a heart attack the first two innings,” Johnson said.

He walked the next two hitters to load the bases before Darin Ruf pulverized a 2-0 fastball off the center field fence. Ruf’s double cleared the bases and gave the Phillies a 3-1 lead. In the first, Gonzalez walked three and threw only 17 strikes in 37 pitches.

Jimmy Rollins and Kevin Frandsen smacked consecutive one-out singles, and it appeared Gonzalez may be headed for an early exit. He escaped the inning without allowing another run. He found Johnson in the dugout and told him, “Skip, I got this. Stay with me.”

For the remainder of his start, Gonzalez allowed two hits and walked none, striking out six. At night’s end, he ranked sixth in ERA, fourth in strikeouts.

“A lot of people can pitch well when things are going good,” Suzuki said. “But it’s the guys that can really bear down when they need to when things aren’t going their way or they aren’t feeling their greatest.”

The Nationals left Citizens Bank Park for the final time this year, headed for St. Louis and, they hope, the biggest celebration in their history. At 95 wins, they can reach 100 with a 5-1 finish. “I only care about three more,” Johnson said.