At 7:50 p.m. ET, Marlins top prospect Sixto Sánchez fired his first MLB pitch, a blazing 98.4 mph fastball taken for a strike by Trea Turner. It marked what many believe will be the beginning of a promising career.

For a first impression, Sánchez came as advertised, bringing heat -- five pitches touched or topped 100 mph -- while striking out four in five innings in the Marlins’ 5-3 victory over the Nationals in Game 2 of Saturday's doubleheader at Nationals Park.

“It was everything I expected this to be,” Sánchez said through an interpreter. “I've worked so hard for this day to come, and it was actually what I expected. My confidence grew a lot after I threw my first pitch. I thought I was going to throw a ball, but I threw a strike. After that, it was good.”

• Box score

Ranked No. 24 on MLB Pipeline’s Top 100 list, Sánchez showed plenty of poise and pitchability against the defending World Series champions.

Sánchez, who sported No. 73, projects as Miami’s potential ace of the future. But in this shortened 60-game season, the Marlins are counting on the 22-year-old right-hander learning on the fly and contributing in a playoff push.

“You just don't know what you're dealing with as a pitcher until you get here, and then you know, you've got to get better at this, and you've got to get back at that,” Marlins manager Don Mattingly said. “It's going to be up to him, quite honestly.”

The way Sánchez performed in his debut continued what the organization had been seeing from him in scrimmages and during bullpen sessions when he was at the alternate training site in Jupiter, Fla.

A week before being called up, Sánchez faced several big leaguers who are on the injured list in a scrimmage. He pitched that day with a purpose.

“I concentrated to do my best, because I knew that if I did well that I was going to have the chance to be here,” Sánchez said.

Sánchez is helping solidify a hard-throwing rotation that expects to get their ace Sandy Alcantara back from the injured list in about a week.

“He’s going to be a lot like Sandy,” Mattingly said of Sánchez. “He's going to have the stuff. But is he going to continue to get better? Is he going to continue to do all the things he needs to do to be a top-line guy?”

• What to expect from Sixto Sánchez in bigs

By picking up his first big league win, Sánchez also helped the Marlins (11-10) gain a doubleheader split, after they lost 5-4 in Game 1. Miami was the home team in the nightcap, because the game was a makeup from a postponement July 31 in Miami.

Nationals right-hander Wil Crowe, Washington’s No. 5 prospect, also made his MLB debut. Crowe yielded four runs in 3 2/3 innings, including Corey Dickerson’s two-run homer in the third that put Miami up to stay.

"He’s a highly talented prospect, and I don’t know if I’ve ever seen 100 [mph] come out so easy,” Crowe said of Sánchez. “It was cool to face up against him. I’m sure it won’t be the last time we go against each other."

The centerpiece in the 2018 trade that sent All-Star catcher J.T. Realmuto to the Phillies, Sánchez is one of the most heralded pitching prospects the Marlins have had since the late José Fernández debuted on April 7, 2013, against the Mets at Citi Field.

Fernández and left-hander Dillon Peters (vs. Phillies on Sept. 1, 2017) hold the Marlins’ record for most strikeouts in their MLB debuts with eight.

Mattingly said Sánchez will become an elite starter by how he prepares between each start.

“Honestly, for the great ones, tomorrow starts Day 1 of their next start,” Mattingly said. “So it's whatever that routine becomes. It's not like, 'Four days off and I pitch again.' Tomorrow is the first day of his next start. The great pitchers, that's what they have. That's what they do.”

Sánchez came out throwing smoke, with four of his 12 pitches in the first inning reaching at least 100 mph, per Statcast. A couple of fastballs were just about there at 99.7 mph and 99.4 mph.

Juan Soto slapped a two-out single before catcher Francisco Cervelli called for Sánchez to switch things up and spin some sliders. It worked, as his first big league strikeout came on Asdrúbal Cabrera check swinging through a 90.9 mph slider.

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Sánchez finished with 66 pitches (46 strikes), and his four-seam fastball averaged 98.5 mph. Yan Gomes homered in the third and Victor Robles blasted a two-run homer in the fifth, Sánchez’s final frame.

“He’s got electric stuff,” Nationals manager Dave Martinez said. “His changeup was really good, very good. But our guys, I thought we did well. Yan had a big night, hit the ball hard. We stayed on his fastball. I think Robles hit a ball that was up, which was nice to see. But that kid has good stuff. He’s one of their top guys, and he’s going to be in this league for a while.”