PHILADELPHIA -- Bryce Harper placed his hand on his heart before he stepped into the batter’s box with the bases loaded and one out in the bottom of the ninth inning Thursday night at Citizens Bank Park. He felt no heartbeat.

Good.

Harper lives for these moments. He excels in them because he keeps cool. He feels nothing. That calmness helped him crush a 2-2 sinker from Cubs left-hander Derek Holland deep into the second deck in right field for a dramatic, walk-off grand slam in a 7-5 victory.

• Box score

It is the type of moment the Phillies imagined when they signed Harper to a 13-year, $330 million deal in February. It is the type of moment they hope catapults them into a postseason run with 41 games to play. The Phillies swept the series, which could be the start of something. They are tied with the Brewers and just one game behind the Cubs for the second National League Wild Card spot.

“Winning a division, getting to the playoffs, things like that, of course, are great things,” Harper said. “But being able to hit a walk-off homer like that is what you live for.”

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Harper turned on the 95-mph pitch to produce a scorching 113-mph shot. He watched the ball sail toward the second deck. It looked like it could have cleared the ballpark he hit the ball so high. In fact, it was the second-highest homer Harper has hit in the past five seasons.

Once the ball landed, he high-stepped to first base. Then he turned on the jets.

“I was just so excited to get back with the boys at home plate,” Harper said. “Everybody was going nuts. I was trying to get there as quick as possible to celebrate.”

Harper ran from first to home in just 11.3 seconds, according to Statcast. If he ran at that pace the entire way he would have rounded the bases in 15 seconds, which would have been the fifth-fastest trot in the big leagues this year. Instead, it took him 19.3. Still, he ran fast enough to surprise teammate Rhys Hoskins, who was on first base.

“I looked up and I was jumping up and I started to jog, and as I was turning second base, I looked to see where he was at, what kind of reaction he was having, and he was like halfway to second base,” Hoskins said.

Hoskins had to sprint home, too.

Harper barreled into the scrum of teammates that waited for him at home plate. He removed his helmet. He appeared to clock J.T. Realmuto with it.

“He said he didn’t feel anything, so I guess I didn’t hit him,” Harper said. “I went to throw my helmet on the plate. I don’t know. It was awesome.”

Cubs right-hander Yu Darvish allowed four hits and struck out 10 in seven scoreless innings. He threw only 92 pitches, but the Cubs went to their bullpen in the eighth. The Phillies could not have been happier. They scored a run in the eighth to cut the Cubs’ lead to 5-1, then they started to string together their ninth-inning rally.

Cesar Hernandez reached on a one-out error. Scott Kingery followed with a single to right-center, and pinch-hitter Brad Miller singled on a ball that deflected off Cubs second baseman Ian Happ’s glove to score Hernandez. The Cubs summoned right-hander Pedro Strop from the bullpen with runners at the corners, then Roman Quinn hit another ball that deflected off Happ’s glove. Kingery scored to cut the Cubs’ lead to 5-3.

Strop then drilled Hoskins with a pitch on his right hand to load the bases. Hoskins had X-rays after the game.

“I told the doctor I have so much adrenaline right now I don’t feel a lot,” he said. “I think it will probably be fine.”

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Holland entered. Harper ended the game six pitches later.

“I love those moments. I love those opportunities,” Harper said. “I think it helped a lot from a young age, going through those emotions and having those opportunities at 8, 9, 10 years old in big-time games and going to different states and cities and playing for different teams with guys that I didn’t know with expectations and things like that. I just love it.

“These fans do expect that. And I expect to do that for them on a nightly basis. If I don’t, they are going to be there to let me know. I like that, too.”

“Bryce is enormous in those moments, right?” Phillies manager Gabe Kapler said. “He's kind of built for them."

Phillies left-hander Drew Smyly and a few others were in the clubhouse when Harper homered. They roared when they figured out what happened.

“We could hear the stadium rock first because there’s a little delay on the TV, so you knew something good happened,” Smyly said. “Then he just launched it up to the moon.”