DETROIT — So much for the Detroit Tigers rotation shaping up for the postseason.

One step forward, one back.

Max Scherzer will not make his scheduled start against the Twins in Minnesota, due to a recurrence of his deltoid strain, leaving the rotation in flux again.

“Yeah, it’s extremely frustrating that I can’t go out there and help the team. But at the same time, everybody knows that I want to be out there. That’s not the issue,” said Scherzer, who thrives on pitching in big situations, and would love nothing more than to help the Tigers, as they try to protect a slim one-game lead in the American League Central.

“I have an arm injury. I have a deltoid injury. There’s just nothing you can do. Given that, when I’m 100 percent, that’s when I’m going to be out there for the team again.”

Scherzer was skipped two turns ago for the same reason, but made a start Sunday.

The right-hander said his arm felt fine when he threw his bullpen session Tuesday, but he felt his arm tighten up during that night’s game, an “alarming” development in Scherzer’s mind, and said it was “still locked up” the next morning.

He realized he’d “taken a step back.”

“It’s just back to where I was, back to Square One again. That’s the thing where now I have to address it in a more serious manner. Before everyone was on the team plan that if we just got the inflammation out, and my arm felt good, I was good to go. And that’s how I believed this injury was, because it was a deltoid, and not a structural problem. Given that I was healthy for my start, and felt good, to have it flare back up again, now you have to address it in a more intense manner. That’s where I’m at,” he said. “I have no regrets making that start, because I really felt 100 percent, when I went out there on Sunday and made the start. My arm, I was throwing the ball pain-free, discomfort-free. It felt good coming out of my hand.”

Scherzer does not know if he’ll be able to start again in the regular season. After Friday’s start, he was in line to start the regular-season finale on Wednesday, Oct. 3.

“It’s really hard to say. I have to 100 percent listen to my body right now, and I have to listen to what my arm is saying. Right now, my arm can’t throw a baseball,” he said.

“Going forward, with the treatment, hopefully, we’re able to correct this and strengthen everything back up, so I can get back out there as soon as possible. Right now, I just don’t know when that is.”

With the recurrence of the injury, Scherzer does not anticipate going back out on the mound until it’s 100 percent again.

Leyland had already mapped out his rotation through the end of the regular season weeks ago.

“I don’t alternate my plan unless I’m forced to,” said the skipper, who’s also concerned with the lackluster start made by Rick Porcello on Wednesday night, given the “lack of feel” he had. “Sometimes you get surprises.”

Leyland also reiterated that ace Justin Verlander, as of now scheduled to pitch Saturday and then again in either a tiebreaker Game 163 or Game 1 of a playoff series, would not start the season finale.

“He will NOT pitch on three days rest,” Leyland said. “I can guarantee that.”

For Smyly, who started the second game of Sunday’s doubleheader, his first start in nearly a month, the build back up from his long relief role should help him Friday. He lasted 4 1/3 innings Sunday, throwing 78 pitches, something that Leyland will monitor closely again.

“I just would never do anything at any expense to get anybody hurt. So yes, you’re right, I’ll watch it. The fact that he just had the start Sunday should help him some, as far as building him back up a little bit. He’ll still be monitored real close. But I think the fact that he had that start helps,” Leyland said.

“It’s OK, the Twins have got a lot of left-hand hitters. Unfortunately, most of them hit left-hand pitching pretty good.”

[Audio of the interview session with Scherzer is below.]