Cubs 8, Giants 4: Jeff Samardzija struck out 10 over seven-plus innings to snap a 16-game winless streak as visiting Chicago rolled past San Francisco in the opener of their three-game series.

Nate Schierholtz went 2-for-4 with a solo homer and scored two runs for the Cubs, who snapped the Giants’ four-game winning streak and improved to 3-2 midway through their 10-game road trip. Samardzija (1-4) allowed four runs (three earned) on six hits, exiting after allowing Angel Pagan’s leadoff single in the eighth.

Pablo Sandoval homered for the fifth time in his last eight games for the Giants, who struck out 13 times in suffering their fifth loss in 29 contests when scoring first. Yusmeiro Petit (3-2) started in place of Matt Cain (hamstring) and yielded four runs over five frames.

Sandoval, who went 2-for-4 with three RBIs, put San Francisco ahead 3-1 in the fourth with a two-run blast into the right-field seats. The Cubs answered with three runs in the fifth as Darwin Barney lifted a sacrifice fly and Samardzija followed with an RBI double before scoring on Emilio Bonifacio’s triple.

The Cubs moved ahead 6-3 in the sixth, when Welington Castillo and Barney delivered two-out RBI singles off David Huff, who allowed two more runs in the seventh as Anthony Rizzo delivered a run-scoring double before coming home on Luis Valbuena's single. Rizzo and Valbuena were among five players with two hits apiece for the Cubs, who collected a total of 13.

GAME NOTEBOOK: Samardzija, who entered the game with the majors’ lowest ERA at 1.46, earned his first win since Aug. 24, 2013 and reached double digits in strikeouts for the sixth time in his career. … The Cubs’ eight runs are the most scored by a visiting team at AT&T Park this season. ... Chicago optioned OF Ryan Kalish to Triple-A Iowa and activated OF Justin Ruggiano from the disabled list.