De La Rosa, who had made 83 pitches, threw a strike to Troy Tulowitzki and felt a cramp under the forearm above the wrist that locked his index finger in a curled position.
The Dodgers believe De La Rosa didn't drink enough liquids playing in the Mile High City, and he should be ready to make his next scheduled start Saturday.
Catcher Rod Barajas motioned to the dugout that the pitcher was in trouble, and pitching coach Rick Honeycutt and assistant trainer Todd Tomczyk went to the mound.
After a brief conversation, Honeycutt motioned to the dugout that De La Rosa couldn't continue. Ramon Troncoso, the closest thing to a long reliever in the Dodgers' bullpen, was brought in to relieve in a double-switch, with manager Don Mattingly taking out Andre Ethier and putting Tony Gwynn in left field. Trent Oeltjen moved from left to right.
De La Rosa (3-0) allowed a three-run homer to Seth Smith in the first inning and only one hit after that, walking three with six strikeouts in the Dodgers' 10-8 win. On the third strike to Tulowitzki to end the third inning, De La Rosa was clocked at 100 mph.