Montgomery is slated to start Tuesday's game against the Rockies at Coors Field, Jesse Friedman of GoPHNX.com reports.
As expected, Montgomery will return to the Arizona rotation as a replacement for the injured Ryne Nelson (shoulder) following a three-week stint in the bullpen. Montgomery shifted to a relief role after producing a 6.44 ERA over his 19 starts this season, and he didn't fare much better over his four appearances out of the bullpen (4.85 ERA, 1.38 WHIP and 6:4 K:BB in 13 innings). The southpaw covered three-plus innings in three of those relief outings, so he at least should be relatively stretched out as he re-enters the rotation Tuesday.