PITTSBURGH — The moment hardly looked too big for Paul Skenes.

The top-ranked pitching prospect in baseball had a promising major league debut for the Pittsburgh Pirates, working into the fifth inning against the Chicago Cubs on Saturday while offering a glimpse of what might be to come.

Skenes was charged with three runs in four-plus innings. He struck out seven, throwing 17 pitches of 100 mph or more. He also walked two and gave up a homer to Nico Hoerner in the fourth that just reached the first row of bleachers beyond the left-field wall.

As he walked off the field, the mustachioed 21-year-old received a loud ovation from a near-sellout crowd that included his more famous girlfriend, LSU gymnast and social media influencer Livvy Dunne.

Skenes became the first Pirates pitcher aged 21 or younger to record at least seven strikeouts in his major league debut since Nick Maddox fanned 11 against the St. Louis Cardinals in 1907 — 95 years before Skenes was born.

The Pirates teased Skenes’ call-up on Wednesday after he breezed through seven starts at Triple-A Indianapolis. His arrival gave PNC Park a playoff-like atmosphere, or at least as much as it can feel like the playoffs in mid-May for a team that hasn’t reached the postseason since 2015.

Fans lined up two and three deep behind the Pirates’ bullpen beyond the center-field fence to try to catch some of Skenes’ pregame routine. Nearby, the team store under the left-field bleachers did a brisk business, with some ponying up $200 for jerseys with Skenes’ No. 30 stitched on the back.

It has been a dizzying rise for Skenes from somewhat anonymous Air Force Academy cadet to College World Series MVP at LSU to first pick in the 2023 draft to possible franchise cornerstone. And yet he looked plenty comfortable.

Skenes, black socks pulled up high against his white pants, confidently strolled out of the dugout and bounded over the third-base line to start what he has likened to the end of one portion of his life and the beginning of another.

A significant portion of the crowd, including Dunne, stood while Skenes warmed up as “Cue Country Roads” by Charles Wesley Godwin blared over the speakers.

Then Chicago designated hitter Mike Tauchman stepped into the batter’s box, and hype gave way to reality. Skenes unfurled his 6-foot-6 frame and, with his funky delivery, fired a 101 mph fastball to Trautman that plate umpire Paul Clemons called a ball.

Six pitches later, Trautman was walking back to the dugout after swinging at another fastball — 100.9 mph this time — that he tipped into catcher Yasmani Grandal‘s mitt for Skenes’ first strikeout.

His second followed three pitches later.

Cubs right fielder Seiya Suzuki took a pair of called strikes — the second an 87 mph slider that left Suzuki shaking his head — before flailing at another slider.

Chicago center fielder Cody Bellinger worked a walk, but only after taking a ball that registered 101.9 mph, the fastest by a Pirates pitcher since Major League Baseball began tracking pitch speed in 2008.

Skenes worked out of the inning by getting Christopher Morel to fly out to deep center. A walk, a hit batter and a single in the second loaded the bases with one out. No matter. Yan Gomes struck out looking at a fastball, and Tauchman grounded out to second.

The next two innings were more of the same, with Skenes mixing triple-digit fastballs with off-speed stuff that remains a work in progress. Hoerner went deep on a hanging first-pitch slider.

Pittsburgh manager Derek Shelton, who has stressed the team will remain mindful of Skenes’ workload, took the rookie out after his pitch count reached 84 following a pair of hits by the Cubs to lead off the fifth. The runners later scored when reliever Kyle Nicolas walked in a pair of runs.

Pirates general manager Ben Cherington said a few hours before the first pitch that Skenes has nothing left to prove in the minors, even with the outsized attention he has received every step of the way.

“There is no reason to put any ceiling on [him],” Cherington said. “It will be fun to watch that play out. That’s all I can say. I’m very confident that’s how he’s thinking about it. That’s the fun of it for someone like him and some of the other elite performers. It’s finding a way to find that next level.”