DENVER - Jhoulys Chacin's strong start ended painfully.
Chacin pitched effectively into the seventh inning and became the first Rockies starter to throw 100 pitches in a game since last June before leaving with an injury as Colorado beat the Arizona Diamondbacks 3-1 Friday.
"I'm a little bit worried because I don't want to miss a start," Chacin said while wearing a wrap around his lower back. "I want to keep pitching, especially with how we're playing now. Everything is going well and I just want to keep helping my team."
Troy Tulowitzki hit a two-run homer and Chacin helped himself by driving in a run with a sacrifice fly as the Rockies won their seventh in row and remained unbeaten in seven home games this season.
Chacin (3-0) grabbed his lower left back after throwing his fourth pitch to Arizona's Cody Ross with one out in the seventh inning. He was taken out of the game after a brief conference near the mound with manager Walt Weiss and team trainers and replaced by reliever Wilton Lopez.
The team said Chacin, who allowed three hits in 6 1/3 innings and struck out five, exited the game with left oblique stiffness and would be re-evaluated today.
Chacin was pitching a gem before the injury.
"He threw all of his pitches over for strikes," Diamondbacks manager Kirk Gibson said. "We never really got ahead of him. He got the slider over a lot early in the count and we laid off of that. That's probably the best I've seen him throw."
Chacin faced the minimum through four innings, inducing Paul Goldschmidt to ground into an inning ending double play after allowing his first hit, a single by Gerardo Parra, to start the fourth.
In the fifth, Chacin worked out of a two-out, bases-loaded jam by fanning his Arizona counterpart, Ian Kennedy. The Diamondbacks got an unearned run on third baseman Nelson's throwing error in the ninth before Rafael Betancourt closed the game out for his sixth save.
Kennedy (1-2), who allowed three runs on three hits in six innings, was overpowering early. He retired the first 10 batters he faced, half of them on strikeouts.
• What: Diamondbacks at Rockies
• When: 5:10 p.m.
• TV; radio: FSAZ; 1490-AM, 104.9-FM