Cook (14-8, 3.87 ERA) had not been fully healthy since pitching three innings in the All-Star Game. He lost his past two starts, including one against the Nationals at Coors Field.
With Cook rejoining the rotation, right-hander Ubaldo Jimenez's next start will be on Tuesday against the Dodgers, and left-hander Jeff Francis will start on Wednesday.
In other injuries:
Garrett Atkins, who missed the first two games against the D-Backs with strep throat, returned to the starting lineup on Friday. Atkins entered in the fifth inning of Thursday's 6-2 loss.
Catcher Yorvit Torrealba, whose sore left knee drove the Rockies' decision to call up Adam Melhuse from Triple-A Colorado Springs on Thursday, felt much better Friday and went through normal pregame activity. Hurdle said he may start Torrealba on Saturday.
Outfielder Scott Podsednik, out since July 28 with a broken left pinky, will take full-scale batting practice on Saturday and likely begin a Minor League rehab assignment next week.
Outfielder Ryan Spilborghs, out since July 9 with a left oblique strain, is gradually increasing his baseball-related activity. He'll remain with the club throughout the entire road trip, after which he may be ready for a rehab assignment.
First baseman Todd Helton is nowhere near recovered from his back strain. Head trainer Keith Dugger said Helton progresses as long as the team keeps him on light activity, which means no swinging the bat.
Thomas Harding is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.