Giants 3, Rockies 0: Madison Bumgarner retired the first 21 batters he faced en route to a one-hit shutout and Buster Posey provided all the offense with a pair of home runs as host San Francisco ended its three-game losing streak.

Posey slugged a two-run homer in the sixth and a solo shot in the eighth as the Giants stretched their lead in the race for the second wild card in the National League to 1 1/2 games over Atlanta and Pittsburgh. Bumgarner (15-9) tied a career high with 13 strikeouts in a dominant 103-pitch gem, improving to 5-1 against Colorado at home.

Justin Morneau's double to begin the eighth broke up Bumgarner's bid for a perfect game, but the Rockies had their four-game winning streak in San Francisco snapped. Jorge De La Rosa (13-9) stuck with Bumgarner before serving up the blast by Posey with no outs in the sixth and immediately departed with a left thumb contusion.

With the exception of the first inning, Bumgarner struck out at least one batter in every frame - including three straight on two occasions - to register his third career shutout and second this month. He has 49 strikeouts against two walks in five August starts, during which he has posted a 1.58 ERA.

Hunter Pence worked a walk to begin the sixth and Posey hammered a 3-1 hanger into the left-center field seats to give Bumgarner all he would need. Morneau cranked a clean double into right to start the eighth before Bumgarner struck out the next four hitters on a total of 14 pitches.

GAME NOTEBOOK: The last no-hitter in the majors was recorded by San Francisco RHP Tim Lincecum on June 25 and the most recent perfect game in the National League was by Giants RHP Matt Cain in 2012. ... De La Rosa was charged with two runs and four hits while striking out five in five-plus frames. ... Bumgarner is 17-0 in games in which he records at least 10 strikeouts, tied with Denny McClain (1963-72) for the second-best mark in MLB history. Dean Chance was 18-0 in such efforts from 1961-71.