If ever the Cubs would need classic Kyle Hendricks it’s now, in the thick of a playoff chase.

Marcus Stroman’s right rib cartilage fracture will keep him out indefinitely, and the Cubs hope reliever Drew Smyly will be up to the task when he starts Tuesday, so Hendricks is the next best bet behind Justin Steele.

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On Sunday, Hendricks delivered during a 4-3 win over the Royals — backed by home runs from Seiya Suzuki and Miguel Amaya — to close out the series 2-1.

During a challenging August in which his ERA inflated to 4.00, he showed a little vintage Hendricks, touching 90 mph a couple of times.

“Yeah, it’s been a while,” Hendricks said. “I mean, it definitely shows me I’m doing the right things. And I’m where I need to be strength-wise.

“You do get a little pumped, and I think the guys get excited behind me when they see it.”

That includes manager David Ross, who added, “That was cool, that was really nice. So it’s like getting back to some of the velocity.”

Hendricks finished with five hits, three strikeouts and one walk in 6 1/3 innings. He threw 90 pitches, 58 for strikes.

The Cubs gained a game on the Reds in the National League wild-card race with Cincinnati’s 10-3 loss to the Blue Jays, but they remained three games behind the Brewers in the Central Division after they beat the Rangers 6-2.

With possibly eight starts left in the regular season, Hendricks underscored the importance of recapturing his form.

“I had some starts (like Sunday) earlier this year, maybe, but it’s putting those together consistently, putting that stretch together and staying in my mechanics,” he said. “So it’s real close.

“It’s just there’s a few pieces missing right now: my curveball, (holding) runners on base, couple of things. So if I can bring all that together, my heater command and my changeup are the best they’ve been in a long time. So that’s really what I’m relying on.”

Hendricks pitched out of a fifth-inning jam after giving up a double that put a runner on third, and another big moment came in the sixth when he got Salvador Perez chasing a changeup.

Hendricks posted the third start this season in which he’s lasted at least 6 1/3 innings while allowing a run or fewer.

“It’s key for the bullpen for sure,” Ross said. “Being able to keep guys fresh down there during this stretch we have here, no off days coming up. … Things pop up from day to day down in the bullpen, somebody’s not available.

“To be able to get him through the six (innings) was really important.”

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Ross said even in Hendricks’ 10th year he’s still refining his game.

“He’s constantly evolving, to be honest with you,” he said. ”The thing about a career is you come in with a lot of talent and some success and you learn how to play at this level or pitch at this level.

“He did a really nice job early on with his stuff and … had a little bit of setback there last year, some change, was pitching through some injuries and worked his way back. And now he’s found a new version of how he wants to go about things and build him back up to the velocity there.”

Ross singled out the mechanics of his changeup to Perez: “Got some swing-and-miss.”

“Just, like, little bitty details that you can do as a veteran that will continue to evolve, and he’s a big part of us, man.”

Meanwhile, Ian Happ singled for a fifth straight game, Nico Hoerner had five hits in the three-game series and Cody Bellinger’s RBI was the encore to a two-homer, four-RBI performance in Saturday’s 6-4 win.

Here are three other takeaways from Sunday.

Suzuki’s fifth-inning homer was his first since Tuesday against the White Sox, and his five bombs already have matched May’s output.

Miguel Amaya’s eighth-inning jack was his fourth first-pitch homer.

Turns out they would need both insurance runs to eke out a 4-3 win.

“Those were big runs,” Ross said. And we’ve done a nice job with that. I feel like over the season probably as good as any team I’ve been manager of we have we’ve done a we’ve done a nice job of adding on runs.”

What stood out for Ross, however, was how loose Suzuki was, and how Amaya backed his offense with solid defense.

After struggles in June and July, Suzuki found himself out of the lineup earlier this month. Ross believed he was putting the weight of expectations — in Chicago and Japan — on his shoulders.

Suzuki has hits in eight of his last nine games.

“I think it’s just like a little bit of reset, and it looks like he’s having fun,” Ross said. “I’ve never seen him smile, run around the bases yelling in the dugout, and I think he’s just having really good time.”

Suzuki acknowledged,” I’m having fun a lot playing baseball.”

“There was a span where I wasn’t playing, I wasn’t out there on a regular basis,” Suzuki said through a translator. “During that time, I took some time out and thought to myself, ‘What can I do to make myself an even better player?’ And I think because of that time span, I’m getting those results right now.”

Meanwhile, Amaya did a “nice job behind the plate,” Ross said. “(He was) handling Kyle, and Kyle seemed to be moving the ball around really well.”

With Marcus Stroman sidelined, the Cubs are having to cobble together a rotation, but they’re OK with throwing the reliever out there against the Tigers in Detroit.

Ross said he’s “just hoping he can build off a little couple of performances out of the ’pen.

“There’s some analytic numbers that point to leaning toward him, there’s some experience leaning toward him, I think there’s value of (having) Hayden (Wesneski) out of the ’pen.”

Smyly had a mixed bag as a starter, but as a reliever his ERA improved from 5.01 (7-8 record) to 4.09 (2-0) and his strikeout-to-walk ratio rose from 2.65 to 4.67.

But Ross remains confident Smyly can maintain his level.

“We’ll kind of judge the performance as it goes, like we do every starter,” he said. “If he’s rolling, we’ll let him go.

“(Smyly’s) done a nice job of staying conditioned to give us length. Although he’s given some short outings, I think he feels like it’s a good place to give us a nice long start.”

Entering Sunday’s start, Hendricks had allowed 15 stolen bases, tied for 11th in the NL. His 6% caught stealing percentage coming into the game would be a career low.

So of course the Cubs had that weakness in his game on their radar — and they knew the Royals would too.

“We’re trying to keep the stolen base at a minimum — guys have run on him,” manager David Ross said before the game. “To some extent, this team here will run … so controlling the running game is something that’s on our radar as a whole, especially when you play a team like this, I think they’re No. 1 in the league in the second half in stolen bases.”

Indeed, the Royals lead baseball in stolen bases (44) since the All-Star break. The Cubs are tied with the Nationals for second at 38.

On Sunday, Hendricks saw Kansas City steal three bases while he was on the mound, including two in the first inning: Bobby Witt Jr. stole second after hitting the game’s opening single, and Witt scored on Michael Massey’s single to right.

Hendricks said holding runners is something he’s been working on and will continue to emphasize this week.

“I’m giving guys too easy the chance over there, kind of getting predictable with my times,” he said. But again, I’ve got to be able to execute pitches too. So I’m kind of in that in-between a little bit, when to just focus on executing and when to focus on them over there.”