James Kaprielian, the New York Yankees' top pitching prospect, will have Tommy John surgery next week and be sidelined until 2018.
The team said Dr. Neal ElAttrache will operate Tuesday on the 23-year-old right-hander out of UCLA, who was taken with the 16th overall pick in the 2015 amateur draft.
Kaprielian's 2016 season was cut short in April after his third start at Class-A Tampa because of a strained right flexor tendon. He returned to pitch in the Arizona Fall League and went 2-3 with a 4.33 ERA in seven starts, striking out 26 in 27 innings.
He was limited to one major league spring-training appearance, striking out three in two scoreless innings against Toronto on March 16, then was assigned to Class-A Tampa again for the start of this season.
The team said he felt right elbow pain on April 6 and put him on a minor league disabled list. He then had scans and was examined by team physician Dr. Christopher Ahmad.
"I feel for the kid. He worked very hard to get back," Yankees manager Joe Girardi said. "It wasn't meant to be, and my heart goes out to him. You see the look in his eyes every time he takes the mound, and you understand how bad this kid wants to be here and to pitch in the big leagues."