It started Thursday night against the San Francisco Giants.

The stretch run. The pennant race. Whatever you want to call it.

The late-season push that has been missing from Cubs baseball for at least six years returned with two on and nobody out in the top of the fifth inning Thursday night at Wrigley Field – when manager Joe Maddon yanked visibly upset starter Jason Hammel with a 5-2 lead after a pair of walks.

“I did not want to let them back into that game right there,” said Maddon after the Cubs had held on for a 5-4 victory over the defending World Series champs. “It’s been my experience when you get to the playoffs, there’s some really great work done in the fifth, sixth and seventh innings by the relievers that never get any credit for it.”

Wait a minute. Playoffs?

With 56 games left in the season, that’s where the Cubs see this thing going. That’s where Maddon is a week into August – with a team in transition, a low-scoring lineup and a chance.

“Right now as we get into this particular juncture of the season you don’t want to just give anything away, especially when you have a lead like that,” said Maddon, whose team moved a half-game ahead of the Giants in the race for the National League’s second wild-card spot.

Thursday night’s decision in the fifth was just about Thursday night’s game, Maddon said. But clearly, this is how he’ll approach similar situations over these last seven weeks.

“It’s not lack of confidence [in Hammel] by any means. It’s just the moment,” he said. Every game has it’s own unique characteristics.”

This one included a 5-0 lead the Cubs took against Chris Heston on rookie Jorge Soler’s two-run single during a 38-pitch first inning, and a three-run homer by rookie Kyle Schwarber in the second.

“You get off to such a quick lead like that, to relinquish that and lose that game is a very difficult loss,” Maddon said, “especially to this particular team right now.”

Hammel clearly wasn’t happy about the decision, even after talking with Maddon after the game.

Asked if he understood it, Hammel said, “Yes. Yes and no. I felt like I’d earned the right to kind of get out of that situation. It is what it is. He leveled with me, and we’re on the same page.

“I understand the magnitude of the situation, and I don’t want to make a big deal of it,” added Hammel, who said he felt the best physically he has this season. “Obviously, as a competitor I want to be out there and clean up my own mess. Honestly, I thought [umpire] Manny [Gonazlez] had a pretty tight zone today, and some of the pitches that missed could have been strikes. Joe told me nobody told him about that. So it is what it is.

“The bottom line is we won the game.”

Hammel experienced a lot of deep counts even in retiring 11 of the first 12 he faced, then gave up a two-out, two-run homer to Brandon Belt in the fourth before walking the first two in the fifth.

That’s when Maddon, who liked Hammel’s stuff but not his command, made clear to anyone watching what he believes is at stake. Even in August. Especially against a Giants team that has won three of the last five World Series.

“They’re the ultimate in battle-tested,” general manager Jed Hoyer said before the game. “It’s a good test for our guys, and [the series] obviously has incredible importance as far as the standings.”

Newly acquired reliever Tommy Hunter gave up a two-out homer to Brandon Crawford on a 98-mph fastball in the sixth to make it a one-run game. But he and the next three guys out of the bullpen combined to retire 10 of the final 11 Giants to close it out.

Look for more of these kind of games – with six more left against the Giants, six against NL Central-leading St. Louis, seven against top wild-card leader Pittsburgh and three against the National League West-leading Dodgers.

“These certainly aren’t the last important games we’re going to play, but it is a meaningful August series,” Hoyer said. “And I think that’s great for our guys to test themselves against a team that’s won these battles before.”

Maddon called the atmosphere at the ballpark “fabulous,” the intensity of the game “entertaining” and the energy and vibe in the dugout “almost too entertaining.”

“It was tight. It was intense. It was great,” said Maddon, who took the Tampa Bay Rays to four playoff appearances in the last seven years. “That’s what it’s supposed to feel like. That’s what it’s supposed to look like. That’s what everybody’s looking for.

“I love that kind of moment. I think it’s great, and I want our guys to embrace it.”