Seager exited Friday's game against the Colorado Rockies in the second inning, and he will not be in the lineup for Saturday's clash with Colorado.
Seager is coming off a 2016 in which he won National League Rookie of the Year and finished third in the NL MVP voting.
The 23-year-old had a .308/.365/.512 slash line to go with 26 home runs and 72 RBI. FanGraphs also rated him the seventh-best defensive shortstop, which is more than adequate given his contributions at the plate.
Seager has built upon that production in 2017 with a .298 batting average, 12 homers and 39 RBI for a Dodgers team that is in playoff position.
While the Dodgers have assembled a strong roster and boast Clayton Kershaw, the best starting pitcher of his generation, losing Seager for an extended period would be a big blow.
Los Angeles survived 2016 despite Kershaw's back issues, but he only pitches every five days, whereas Seager is expected to play every game. No player is more important to the lineup than the young star.
Roberts will likely have to turn to Enrique Hernandez, who is batting .230 with seven home runs and 22 RBI this season, to patrol shortstop until Seager can return.