Horton was removed from his start Tuesday against the Mets due to back tightness, Andy Martinez of Marquee Sports Network reports.
Horton made it through three innings of one-run ball Tuesday before his back forced him to make an early exit. His abbreviated outing will likely be his final appearance in the regular season, giving the rookie right-hander a 2.67 ERA and 1.08 WHIP through 118 innings across 23 appearances. As long as his back injury proves to be minor, Horton will certainly be in the running to start Game 1 of the NL Wild Card Series next week.