ST. LOUIS -- While the Cardinals have already clinched a postseason berth, they are still eyeing the National League Central title. The pennant race will come down to this weekend, so the Cardinals altered their rotation to face the Cubs at Busch Stadium.

Dakota Hudson (16-7, 3.45 ERA) started Friday, as planned, but Adam Wainwright (14-9, 3.98 ERA) will now start Saturday on normal rest, pushing Miles Mikolas (9-14, 4.16 ERA) back. Sunday’s starter has not been announced, likely because the Cardinals are waiting to see how the first two games affect the standings.

St. Louis holds a one-game lead in the National League Central over Milwaukee, which has won 18 of its last 20 games, including a victory Thursday at Cincinnati. With the Brewers looming, the Cardinals’ magic number to clinch the division is three, so the earliest the Cardinals could clinch is Saturday. While the Cardinals face the Cubs, who were eliminated from postseason contention Wednesday, in St. Louis, the Brewers will face the Rockies at Coors Field this weekend.

Switching around the rotation allows the Cardinals to have Hudson and Wainwright start the first two games of the series in the hope of clinching the division Saturday. The Cardinals previously listed Mikolas as their Saturday starter, with Wainwright set to pitch Sunday.

“We’re in an opportunity -- and it’s really more about Adam and the way he’s been pitching and the way he’s pitched in games in these situations,” Cardinals manager Mike Shildt said. “It’s not a slight against Miles in the least, but more of an opportunity for Adam.”

Wainwright has a 1.69 ERA in five starts this September, allowing six earned runs in 32 innings. In his career, he has a 3.03 ERA in 24 postseason games (12 starts).

If the Cardinals do not clinch Saturday, they have Mikolas and Jack Flaherty (10-8, 2.85 ERA) on hand to start Sunday or possibly Monday, if the Cardinals and Brewers are tied for first at the end of the weekend and need a tiebreaker game to determine the division championship. That game, if needed, would be at St. Louis because the Cardinals won the season series vs. the Brewers, 10-9.

Flaherty has been the best starter in the Majors in the second half, with a 0.97 ERA, and the Cardinals would ideally line him up to start Game 1 of the NLDS against the Braves. But if the Cardinals don’t clinch Saturday, they will need to decide whether to start Flaherty on Sunday in the hope of winning the division. But because that would remove Flaherty from starting the Wild Card Game or potentially Game 1 of the NLDS, the Cardinals want to lock up the division by Saturday using Hudson and Wainwright.

There’s also a scenario where Daniel Ponce de Leon could start Sunday if the Cardinals win the division Saturday night. Ponce de Leon has made eight starts for the Cardinals this year and is their long reliever right now. He pitched three innings and allowed two hits in the Cardinals’ 19-inning loss to the D-backs on Tuesday. Starting him would allow Hudson, Wainwright, Mikolas and Flaherty to be on ample rest for the NLDS.

“We’ll get through [Friday] and we’ll continue to evaluate,” Shildt said.

Wacha shut down from throwing
One starter who won’t be available for this weekend is Michael Wacha. After exiting Wednesday in the second inning with a right shoulder strain, Wacha won’t throw at all over the next five to six days, Cardinals general manager Michael Girsch said Friday.

Wacha will start to throw again in the middle of next week, putting his availability for a potential Division Series in jeopardy. Wacha felt tightness in his shoulder while warming up for Wednesday’s start, and it got worse as he worked through the game.

Girsch said the strain is unrelated to the shoulder problems Wacha had in 2014 (stress reaction in right shoulder) or '16 (right shoulder inflammation).

“It’s pretty mild,” Girsch said. “Not a huge issue. We hope to have him on the mound in five or six days. We had nothing on the medical report before he made his last start. I don’t know if it was one pitch or if it built up during that start, but until Wednesday, we had no indication of anything.”

Wong encouraged in hamstring recovery
Second baseman Kolten Wong, dealing with a left hamstring strain, participated in full baseball activities Friday after spending the week in St. Louis ramping up his workload. He’ll be evaluated Saturday to determine his availability for the rest of the weekend.

“It’s sort of day to day,” Girsch said. “It’s how he recovers after each day of pushing the activities to another level. He’s feeling good, so we’re optimistic.”

Wong said the pain has gotten better since injuring the hamstring on Sept. 19 at Wrigley Field. He felt good taking swings on the field and said he could run at 70-80 percent. He said he would be ready to play this weekend if needed, but he needs to decide if he wants to push it now or wait for the postseason.

“I’m excited to come back,” Wong said. “That’s kind of what’s getting into the thought of, ‘Do I want to push it now and take the possibility of being out, or do I want to do the smart route and make sure I’m ready for the playoffs?’

“The only thing would be, you step into the game and the adrenaline kicks up, you want to go from first to third and try and push it a little harder. That’s the only thing I’m worried about, I haven’t really gotten a chance to push it yet. Understanding my limits at this point. If need be, I’m ready to go.”