Robert suffered the injury while trying to beat out a ground ball during Sunday's game against the Cleveland Indians. The 23-year-old collapsed in pain after crossing first base, and trainers needed to help him off the field.
The best-case scenario for Robert's return is August, Hahn said, adding that the second-year pro can't be ruled out for the season yet, according to James Fegan of The Athletic.
Robert is slashing .316/.359/.463 this season with one home run and four stolen bases over 25 games. He finished as the runner-up for AL Rookie of the Year honors in 2020 and won a Gold Glove.