San Diego Padres minor league infielder Fernando Tatis Jr. had surgery Tuesday for a broken left thumb with ligament damage.
Tatis is expected to be sidelined at least six to eight weeks, potentially ending his season with Double-A San Antonio.
He was hurt on a headfirst slide while attempting a steal last Thursday.
ESPN's Keith Law had rated Tatis as the No. 1 prospect in baseball at the season's midpoint.
The 19-year-old Tatis struggled in April but was hitting .286 with 16 home runs and 43 RBIs over 88 games in Double-A.
Information from The Associated Press was used in this report.