WEST PALM BEACH, Fla. — Five-hundred days later, Lance McCullers Jr.’s return is imminent.

The Astros’ curveball connoisseur and fan favorite will make his Grapefruit League debut on Sunday against the Cardinals in West Palm Beach — 500 days after his last appearance in a major league game.

One inning seems like McCullers’ limit, Astros manager Dusty Baker said Saturday, but a quick first could allow McCullers a second frame.

“Raring to go ain’t his problem,” Baker said. “If anything, we’re going to have to calm him down. He’ll probably be begging or lobbying to try to go more than one.”

McCullers underwent Tommy John surgery in Nov. 2018, sidelining him for the entire 2019 season. The team adhered to a gradual rehabilitation process for the 26-year-old righthander, who could have appeared in minor league rehab games toward the end of last season.

McCullers faced live hitters last October at the team’s Florida facility, but Sunday will be his first game action since Game 5 of the 2018 American League Division Series — an outing McCullers pitched with a torn ulnar collateral ligament.

McCullers’ return and effectiveness is crucial for an Astros starting staff that appears somewhat vulnerable behind Justin Verlander and Zack Greinke. McCullers was an All-Star in 2017 and owns a 3.67 ERA in four major league seasons.

ASTROS INSIDER: Follow the Houston Chronicle’s spring training coverage as the Astros prepare for the 2020 season.