Paul Skenes, considered the top pitching prospect in baseball, has been lighting up opposing hitters in Triple-A. But the future Pittsburgh Pirates right-hander went through a rite of passage Sunday, allowing his first home run as a pro.

Pitching for Indianapolis, Skenes gave up a solo home run to Buffalo outfielder Will Robertson, a Toronto Blue Jays prospect, in the fifth inning. Skenes had pitched 33 innings in the minor leagues over the past two seasons before allowing his first long ball.

Skenes, 21, got one more hitter out Sunday before leaving after 4 innings, having allowed two runs on three hits with four strikeouts and two walks over 66 pitches.

Even with allowing two earned runs for the first time this season, Skenes' ERA ticked up to just 0.99. He has allowed four total runs (three earned) on 17 hits with 45 strikeouts and eight walks over 27 innings on the season.

The Pirates are expected to call up Skenes at some point in 2024 after they used the No. 1 overall pick on him in the July 2023 draft and gave him a record $9.2 million bonus.

Pittsburgh has been limiting his usage in the minors, as Skenes has thrown no more than 75 pitches in a game this season. Sunday was the first time he's pitched on four days' rest.

Speaking to 93.7 The Fan earlier Sunday, Pirates general manager Ben Cherington said he viewed Skenes' start Sunday as another important step in his journey to the majors.

"We talk about boxes being checked, and today would be another one," Cherington told The Fan. "It's the first time, as a professional ... that he'll be starting a game on four days' rest. It may not seem like a big deal, but it is the first time it'll happen, and it's another box to check. He's been checking just about every box since the season started and responding incredibly well."

Information from ESPN's Jeff Passan was used in this report.