The Rockies recalled Sullivan from Triple-A Albuquerque on Saturday.
Sullivan was optioned to Albuquerque on Tuesday, but he's right back up with the big-league club to make a start in place of Tomoyuki Sugano, who was placed on the 15-day IL due to back spasms. Sullivan has struggled during his time with the big-league club this season, recording an 8.64 ERA, 1.86 WHIP and 12:9 K:BB over 16.2 innings spanning four starts. However, Colorado doesn't have many other rotation options to turn to, so Sullivan could remain in a starting role beyond Saturday while Sugano recovers.