According to Dennis Lin of The Athletic, Tatis has "slight labral tearing" that is "consistent with a subluxation injury."
His official injury designation is left shoulder inflammation.
The 22-year-old left Monday's game against the San Francisco Giants in the third inning after he injured himself swinging. The Padres did not immediately provide any information about his injury, but he left the field with training staff holding onto his arm.
The Dominican was 3-for-16 with a home run and an RBI through four games before the injury, but he had proved to be an integral part of the team in 2020. He appeared in 59 games, hitting .277/.366/.571 with 17 long balls and 45 RBI en route to the postseason.
The team rewarded his effort with a 14-year, $340 million contract this offseason.
Jake Cronenworth and Ha-Seong Kim are also available at shortstop, though neither can fully replace the power provided by the Padres' franchise star.