The team placed Tatis on the 10-day injured list due to a stress reaction in his lower back. Padres manager Andy Green told reporters the injury resulted from "common usage" and will "most likely" end his 2019 season.
"He's had a couple MRIs just to make sure we knew what was going on back there," Green said. "He has a stress reaction in his lower back and is most likely done for the remainder of this season. We'll re-evaluate him here in three weeks.
"Disappointing. Obviously we're going to do what we can to take care of him."
The 20-year-old slugger, who is a Rookie of the Year candidate, was batting .317 with 22 home runs, 53 RBIs and 13 doubles in 84 games this season.
The Padres also placed veteran second baseman Ian Kinsler on the 10-day injured list Friday with a neck injury. The neck ailment is expected to end his season, according to the team.
Kinsler, 37, had a .217 batting average with nine homers and 22 RBIs in 87 games. San Diego recalled infielder Ty France and outfielder Travis Jankowski from Triple-A El Paso in corresponding roster moves.