Rockies 8, Diamondbacks 7: Todd Helton hit a two-run homer with two out in the bottom of the ninth inning as Colorado stunned Arizona.

Helton turned on a 1-1 fastball by J.J. Putz (0-1) and hit a towering shot which landed just inside the right-field foul pole for his first homer of the season and seventh walk-off blast of his career.

Putz, who hit Marco Scutaro to lead off the ninth before retiring pinch hitter Jason Giambi and Troy Tulowitzki, had converted his previous 28 save opportunities.

Colorado took a 3-1 lead in the second inning when Tyler Colvin, filling in for an ill Carlos Gonzalez, hit a two-run homer and Ramon Hernandez followed with a solo shot to center field for his second home run in as many days. The Rockies added single runs in the third and fourth.

Arizona began its comeback in the fifth with a three-run homer by Miguel Montero - his second in as many games - and McDonald's RBI double in the sixth tied it.

Paul Goldschmidt's sacrifice fly in the seventh gave the Diamondbacks a 6-5 lead and Gerardo Parra, who went 3-for-4, drove in McDonald with a safety squeeze in the eighth to make it 7-5.

Eric Young's RBI double in the eighth set the stage for Helton.

Neither starter survived a 1 hour, 11 minute rain delay which came after the fourth inning. Colorado's Jhoulys Chacin allowed four hits and one run while Arizona's Josh Collmenter allowed five runs and five hits. Each pitcher walked three in four innings.

Michael Cuddyer had three hits and Tyler Chatwood (1-0) allowed one run in two innings for Colorado.

GAME NOTEBOOK: Gonzalez has strep throat and could also miss Sunday's series finale. ... The game was also delayed 16 minutes at the start. ... The Rockies have made 12 errors in their first eight games. Tulowitzki made two throwing errors in the sixth inning, the first leading to the tying run. ... Thirteen of Montero's 60 career homers have come against the Rockies, including six at Coors Field. ... All eight of Arizona's games this season have been decided by two runs or less.