Seager won't know for sure until he undergoes an MRI on Wednesday, but Dodgers manager Dave Roberts said "early indications" were that Seager suffered a Grade "2-plus" strain, which typically comes with a recovery time in the neighborhood of six weeks.
"I feel bad," Roberts said after his team's 5-3 loss to the Los Angeles Angels. "We all feel bad for Corey."
Seager singled and advanced on a wild pitch to begin the top of the ninth and probably would've scored easily on Alex Verdugo's ensuing base hit up the middle, but he grabbed at his left hamstring before reaching third base and walked gingerly off the field shortly thereafter.
Chris Taylor and Enrique Hernandez are likely to fill the void at shortstop.
"Just one bad step, I guess," Seager said moments before walking out of the visitors' clubhouse at Angel Stadium.
"Obviously very unfortunate, the way he's been playing and what he means to our ballclub," said Roberts, whose team failed to score despite putting runners on the corners with nobody out in the final inning. "As far as timetable, I think that we'll know more tomorrow."
An All-Star in each of his first two full seasons in 2016 and 2017, Seager, 25, underwent Tommy John surgery 26 games into 2018, then had an arthroscopic procedure performed on his hip in August.
He made it back by Opening Day this year, but carried only a .231/.320/.367 slash line by May 22. In June, though, Seager was batting .389/.421/.667 heading into Tuesday's game, then reached base four times.
"He was swinging the bat well," Dodgers third baseman Justin Turner said. "That's probably part of it -- he was swinging the bat so well he was on the bases three, four times a game. Doubles, first-to-thirds. When you have that kind of volume, and you get hot weather like this, it's almost a recipe for something to come up. Unfortunately it hit him."
Seager comes up limping running to third
As Alex Verdugo comes up with a hit, Corey Seager goes to round third and comes up limping. Seager would leave the game with a leg injury.