The Chicago Cubs placed closer Brandon Morrow on the 10-day disabled list retroactive to June 17 with back tightness.
Morrow was held out of Tuesday's doubleheader against the Los Angeles Dodgers due to back spasms he sustained while taking off his pants.
The right-hander has rewarded the Cubs' decision to extend him to a two-year, $21-million contract - plus a team option for 2020 - this past offseason by recording 16 saves and posting a 1.59 ERA, 1.15 WHIP, and 9.9 K/9 over 22 2/3 innings.
Rookie reliever Justin Hancock will remain with the club after serving as the team's 26th man for Tuesday's doubleheader.