Cincinnati Reds minor league right-hander Hunter Greene, who is considered the organization's top pitching prospect, will have Tommy John surgery, the club said on Monday.
Greene will have the procedure after suffering a setback last week in Arizona. Greene was shut down by the club in August with a sprained ulnar collateral ligament.
Greene began throwing again over the offseason, but suffered a setback last weekend while throwing to batters. An MRI found new damage, Reds president of baseball operations Dick Williams said Monday night.
In 18 starts in 2018 with Class A Dayton, the hard-throwing Greene was 3-7 with a 4.48 ERA and 89 strikeouts in 68⅓ innings.
Greene is ranked No. 16 among the top 100 prospects in baseball, according to ESPN's Keith Law.
The 19-year-old was the No. 2 overall pick in the 2017 amateur draft. He received a $7.2 million signing bonus that was the largest ever for a draftee.
The Associated Press contributed to this report.