With Eric Chavez at third base and Jason Kubel batting, Oswalt threw a 1-2 pitch in the dirt that bounced off of catcher Wilin Rosario and shot to the left of the plate. Oswalt dashed to the plate, but pulled up as soon as he reached for the throw.
The Rockies' training staff attended to Oswalt and quickly led him into the dugout. Right-hander Edgmer Escalona replaced Oswalt.
The addition of Oswalt, 35, a three-time All-Star, hasn't gone as planned for the Rockies. He signed after the season started and pitched in extended spring workouts and at Double-A Tulsa before joining the Rockies for a June 20 debut. He lost all three previous three starts, and Sunday's run placed his ERA at 7.64.
The 1 2/3-inning performance marked his shortest start since he went 1 2/3 for the Astros against the Cubs on July 28, 2009.
Thomas Harding is a reporter for MLB.com. Read his blog, Hardball in the Rockies, and follow him on Twitter @harding_at_mlb. This story was not subject to the approval of Major League Baseball or its clubs.