Seager missed the National League Championship Series against the Chicago Cubs because of a back injury.
The Dodgers won the NL pennant for the first time since 1988 in an 11-1 victory over the defending World Series champions at Wrigley Field.
Roberts also said Clayton Kershaw will start Game 1 on Tuesday night at Dodger Stadium, and the team will figure out the rest of the rotation at a later time.
Said Kershaw about the ALCS: "Hopefully, they go seven games and play 37 innings in the seventh game."
Information from The Associated Press was used in this report.