Iannetta sent an 0-1 pitch from Hunter Strickland (2-2) up the middle to score Nolan Arenado.

Trevor Story hit a three-run homer and scored three times for Colorado. Bryan Shaw (2-3) got the win with one scoreless inning of relief.

Evan Longoria had two doubles, a single and three RBIs, and Gorkys Hernandez homered for the Giants.

Arenado walked to start the 10th, and he moved to second on Story's flyout to center field. After Carlos Gonzalez was intentionally walked, Ian Desmond singled to right, and Iannetta followed with his game-winning hit.

The Giants jumped on Rockies starter Chad Bettis early to take the lead. Hernandez led off the game with a single, Buster Posey moved him to third with a one-out single and both came home on Longoria's double to left to make it 2-0.

Colorado wasted little time responding against San Francisco starter Andrew Suarez. With one out in the bottom of the first, Noel Cuevas singled, Arenado walked and Story hit his 11th home run to the seats in left to give the Rockies a 3-2 lead.

Hernandez tied it when he hit the first pitch of the third into the seats, and San Francisco threatened for more with two on and no outs in the frame. However, Brandon Belt grounded into a double play and Longoria grounded out to end the inning.

The Rockies answered again in their half of the third. Story reached on an error, and two straight singles, the second by Desmond, drove him in to give Colorado a 4-3 lead.

The Giants went back ahead in the sixth when Belt led off with a single and came home on Longoria's second double of the game. After a fielder's choice wiped out Longoria, Kelby Tomlinson and pinch hitter Pablo Sandoval had consecutive singles to score Brandon Crawford and make it 5-4.

The Rockies tied it in the eighth on Desmond's sacrifice fly off reliever Tony Watson that scored Story.

Bettis gave up five runs on 10 hits in six innings, while Suarez allowed four runs (three earned) on five hits in five innings.

--Field Level Media