Cahill was hit on the right hip by a line drive off the bat of Marcell Ozuna in the top of the first inning. The ball deflected to third baseman Martin Prado, who threw Ozuna out to retire the side.
Cahill came out to warm up for the second inning and before he threw a pitch to leadoff hitter Derek Dietrich, Arizona pitching coach Charles Nagy visited the mound with one of the team's trainers.
Cahill was left in the game, but after falling behind Dietrich 2-1, Nagy and the trainer came out once again and this time they removed Cahill and brought in right-hander Josh Collmenter.
"I thought I could get through it," Cahill said, "and they just didn't want to risk anything. It was sore, my stride was a lot shorter, but I felt like I could have made an adjustment and pitched through it."
The D-backs already have Brandon McCarthy on the disabled list and are without the services of Ian Kennedy for 10 games due to a suspension, so they did not want to take any chances with Cahill.
"He said he could power through it," manager Kirk Gibson said. "But just watching him warm up it didn't seem like he was pushing off very good and we were worried about him hurting his arm."
Josh Collmenter saved the bullpen by throwing six scoreless innings of relief of Cahill, the second-longest relief stint in franchise history.
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.