Blake Snell struck out a career-high 15 batters, Patrick Bailey broke a seventh-inning tie with a two-run double and the San Francisco Giants defeated the visiting Colorado Rockies 4-1 in the opener of a doubleheader Saturday.

Snell worked six shutout innings, allowing two hits and two walks, before giving way for Ryan Walker (7-3), Tyler Rogers and Camilo Doval for the Giants' second straight win to begin the four-game series.

The 15 strikeouts were two more than Snell ever had in his nine-year career. Only three of his 18 outs were not strikeouts. Kris Bryant lined out in the first and Jacob Stallings flew out in the second and fifth.

The left-hander was pulled before Bailey's big hit, leaving him winless in 10 starts to start his season.

Rockies right-hander Ryan Feltner, whose only win in 11 decisions this season came in Toronto in his third start of the season, also worked six innings, allowing one run and four hits. He walked four and struck out six.

Thanks to Matt Chapman's solo home run in the second inning, his 15th blast of the season, the Giants led 1-0, and it stayed that way when the starting pitchers were pulled after six innings.

Michael Toglia tied the game with a solo home run with one out in the seventh off Walker.

The Giants also took advantage of a pitching change in the last of the inning, putting two runners aboard against Justin Lawrence (3-4) when Jorge Soler reached on Toglia's error at first base and LaMonte Wade Jr. was hit by a pitch.

Heliot Ramos' grounder advanced the baserunners with a second out, making the Giants 0-for-10 with guys in scoring position to that point, before Bailey lined his tiebreaking hit to left-center. San Francisco finished 1-for-12 with runners in scoring position.

San Francisco tacked on in the eighth when Chapman doubled, took third on an errant pickoff attempt by Peter Lambert and scored on a wild pitch.

Chapman finished with a homer, double, single and two runs for the Giants, who outhit the visitors 6-4.

--Field Level Media