Philadelphia Phillies right-hander Andrew Painter has a sprained ulnar collateral ligament and will not throw for four weeks before the team reassesses whether he can continue to pitch through the tear in his elbow, it was announced Friday.

Painter, who turns 20 on April 10, is the No. 10 prospect in baseball, according to ESPN MLB Insider Kiley McDaniel. He was expected to push for major league playing time this season after blowing through the Phillies' system last year in his first full season.

The 13th pick of the 2021 draft, Painter mixes a fastball that approaches 100 mph with a devastating slider along with a changeup and curveball.

After an initial diagnosis of a UCL sprain -- a sprain is a tear of a ligament, though the Phillies did not announce the degree of it, which would be a better indicator of the severity -- Painter sought a second opinion with Dr. Neal ElAttrache, who confirmed it.

Pitchers can continue to play with UCL tears, though it often leads to Tommy John surgery. Phillies ace Aaron Nola missed the final six weeks of the 2016 regular season with a partially torn UCL -- and has thrown the most innings in the National League since. Similarly, former New York Yankees starter Masahiro Tanaka spent most of his career with the Yankees throwing with a tear in his UCL.

The location of Painter's sprain, on the side of the ligament that attaches to the medial epicondyle, bodes better for potentially avoiding surgery. In a 2017 study, researchers studied 32 professional pitchers with UCL tears. Of the 19 who had tears in a similar location to Painter's, 17 avoided surgery.

In 103⅔ innings last season across three levels and topping out at Double-A, Painter posted a 1.56 ERA with 155 strikeouts, 25 walks and five home runs allowed.