ST. LOUIS -- As the only rookie on the Cardinals' roster on Opening Day, Andre Pallante quickly became something of an unexpected savior when he admirably filled the often-overlooked role of bridge reliever between the starters and the back end of the bullpen.

Now, with three starting pitchers on the injured list, the 23-year-old Pallante has changed roles to give the Cardinals just the jolt they need from the starting rotation. After Pallante went out and fired 5 1/3 scoreless innings in a 2-0 win before a sellout crowd of 45,009 at Busch Stadium on Friday night, manager Oliver Marmol said that the Cards likely would be nowhere near first place in the NL Central without Pallante's pitching versatility.

"One of the most impressive things is his ability to slow everything down, and he continues to do that regardless of whatever situation we put him in, regardless of whether he's coming out of the 'pen or starting," Marmol marveled. "It doesn't matter. Today was fun because we had a packed house, and he was under control the entire time."

How impressive has the Cal-Irvine product been for the Cardinals? After making just one MLB start last week, Marmol declared him a starter and definitively said Pallante "will throw every fifth day." That's just fine with the precocious Pallante, who left the mound with a 1.04 ERA. However, the young pitcher gave some insight into his immense drive to be great when he gave a rather harsh review of an outing where he allowed just four hits and struck out four batters.

"I still walked two guys [in the first inning] and it's unacceptable to go out there and not be ready," said Pallante, who worked his way out of that early jam and breezed the rest of the way. "After that, I felt like I did a good job of settling down and keeping my fastball down. I found my curveball toward the end, and I got a lot of ground balls."

As impressed as the Cardinals were about Pallante's pitching, several Reds were even more shocked after seeing his hard cutter for the first time. After whiffing on a 94 mph fastball from Pallante in the third inning, Reds first baseman Joey Votto stepped out of the box, looked into St. Louis' dugout and let out a hearty laugh about his weak offering at the pitch. Afterward, Cincinnati manager David Bell was even more effusive about the stuff he saw from Pallante, who is already drawing comparisons to reigning NL Cy Young Award winner Corbin Burnes.

"He's definitely a different look," Bell said of Pallante. "Our hitters were saying it was difficult to really tell what was coming out. We were obviously prepared, but definitely he's a different look. He has a really good arm. The [scoreboard] was saying 96 or 97 [mph], but it looked like 110 [mph] from my angle. It was the first time we've seen him. It was a great start."

Somewhat of a surprise addition to the Opening Day roster, the fourth-round pick in the 2019 MLB Draft impressed the Cardinals with his high ground-ball rate. What has surprised them however has been the righty's ability to offer up reverse splits against left-handed hitters. Because the movement on his cutter is so sharp and late-breaking, left-handers have only offered up mostly weak contact against him this season.

That was the case again on Friday, when the eight at-bats by left-handers against Pallante got to him for just one hit. For the season, left-handers are hitting just .182 against Pallante.

"My fastball kind of does whatever it wants sometimes. I kind of use my four-seam fastball grip and sometimes it cuts and sometimes it sinks," Pallante said matter-of-factly. "It's why I have a high ground-ball rate. My fastball has a lot of depth to it and it kind of goes down. The team trusts me to get ground balls."

Clearly, the team also trusts him in big spots. From Pallante's first high-leverage spot of the season -- when he was inserted into the game on April 20 with the go-ahead runners on base and he came through -- he has shown the Cardinals that no stage is too big for him. Marmol said the one regret in moving Pallante to the starting rotation is that it "leaves a bit of a hole," referring to the spot where he usually gets the ball to the club's three-headed closing grouping of Génesis Cabrera, Giovanny Gallegos and Ryan Helsley.

"The kid does not care where he's at," Marmol said. "He studies the game and he's a baseball rat. As far as the moment, a big stadium or a packed house -- not only does it not bother him, he doesn't care."