During the course of the Red Sox's loss to Marcus Stroman and the Blue Jays on Thursday (TOR 8, BOS 0), Boston DH David Ortiz was forced to exit the game with what was later described as back spasms. Ortiz sustained the injury while checking his swing in the ninth inning. Manager John Farrell characterized Ortiz's status as "day-to-day."
This season, Ortiz is batting a productive .253/.348/.505 (136 OPS+) with 24 homers in 98 games.
Obviously, the injury doesn't sound serious at this juncture, but bear in mind that Ortiz is a 38-year-old DH. As such, his status is worth monitoring.