The sun came out, and after days of freezing temperatures the air was a little nicer at Coors Field on Friday night. It wasn't quite summer, but jackets and Jhoulys Chacin's masterful pitching kept Rockies fans among the 23,445 warm for 6 1/3 innings.

That was before the first significant storm cloud set in over the Rockies' season.

Troy Tulowitzki homered for the fifth time and the National League West-leading Rockies won their seventh straight, 3-1, over the D-backs. But the joy was tempered when Chacin grasped his back and side on consecutive seventh-inning fastballs and was removed. He was diagnosed with left oblique stiffness and will be re-evaluated on Saturday.

The victory in the opener of a three-game weekend set put them at 4-0 on a nine-game homestand. It was originally scheduled for 10 games, but one was wiped out by the snow that hit earlier this week. The Rockies also are now 7-0 at Coors Field.

Chacin (3-0) struck out five against one walk and held the D-backs to three hits. It's not known how much longer he would have pitched, since he came out after pitch No. 100.