KANSAS CITY -- The Cardinals have operated with little room for error in August, a margin that was made all the dicier when they were swept by the Braves in the month’s first full series.

Their response has been swift, stellar and with swagger. It bubbled into two innings on Sunday, scoring seven runs in the first two frames off starter Kris Bubic for a 7-2 sweep-securing victory over the Royals at Kauffman Stadium, representing their eighth triumph in their last nine games.

But their response will be further tested, more than it has over the course of this six-game winning streak against the last-place Pirates and Royals. Now St. Louis welcomes the first-place Brewers and their historically great trio atop the rotation, all set to pitch at Busch Stadium from Tuesday to Thursday. It’ll mark the clubs’ first matchup since May; they face each other 13 times down the stretch.

“We’re ready for Tuesday,” said manager Mike Shildt. “I’ll tell you that.”

The statement made on Sunday -- and over the course of three days across I-70 -- was on the backs of Nolan Arenado and Paul Goldschmidt. The duo led the Cardinals’ 1-4 hitters with four RBIs through the first two innings, including Arenado’s two-run long ball to give himself a homer in each game this series. By the time the third inning rolled around, the top of St. Louis’ lineup was 7-for-8 with seven runs scored and five RBIs.

Shildt has said that coordinated hot streaks of Arenado and Goldschmidt -- solid this season but seldom at the same time -- is like a movie premiere: “Coming soon, to a ballpark near you." And it may have arrived.

“You get that kind of contribution to the middle of the lineup, guys like that, it's huge,” Shildt said.

They gave J.A. Happ plenty of room for error before he stood on the mound on Sunday. He responded with his second consecutive win in a Cardinals uniform, with a 1.62 ERA in tow after 5 2/3 shutout frames. Happ’s ascent in prominence (and descent in ERA) has been emblematic of the Cardinals’ own excellence in starting pitching since the Trade Deadline, third in the league by ERA standards. The only two ahead of them: Milwaukee and Los Angeles.

The former will enter Busch Stadium 25 games over .500 while throwing its three best pitchers St. Louis’ way. Corbin Burnes, Freddy Peralta and Brandon Woodruff are lined up to start the midweek series; they make up three of the top five ERAs and three of the top 10 fWAR totals in the Majors.

The Cardinals will punch back with a rock-solid trio of their own; Adam Wainwright, fresh off a two-hit shutout on only 88 pitches, will be followed by Jack Flaherty, set to make his second start since returning off the injured list and look to one-up his own six shutout frames.

Thursday’s starter is to be announced; the Cardinals are weighing Miles Mikolas, who handed in what was likely his final rehab outing on Saturday, or Jon Lester, who has been historically solid against Milwaukee.

“It's going to be a battle, but we're playing good baseball and we're confident with what we have and what we can do,” Arenado said. “We're excited for that series.”

But that the Cardinals find themselves in the thick of a decision with more serious implications to make -- like Thursday’s starter -- is because of the play they turned in across the state, capping off only the second undefeated road trip of at least six games in franchise history.

They allowed just six runs in three games to the Royals and scored 22 of their own. They’re averaging 5.15 runs per game through 13 games in August while averaging 3.19 and 4.17 in June and July, respectively. It simply came in an unrelenting manner on Sunday.

The Cardinals’ 2021 season to this point has been a roller-coaster ride of consistency, of results and of injuries. Despite it all, it has landed them in the thick of the National League Wild Card chase, with the Padres ailing and six games left against the Reds they’re also chasing.

On their docket? Three of the top 5 pitchers in the Majors by ERA, seven games against the Pirates and two more against the Tigers before the month draws to a close and the playoff push kicks into its highest gear.

“This is why I’m here,” Arenado said.