Cubs 8, Giants 5
SAN FRANCISCO -- Kyle Schwarber, Miguel Montero and Starlin Castro hit home runs to back the powerful pitching of Jake Arrieta, leading the Chicago Cubs to an 8-5 victory over the San Francisco Giants to kick off a three-game series of playoff contenders Tuesday night.
The win in the opener of a six-game Western swing was the Cubs' sixth in a row and ran their best-in-baseball road record to 34-25.
Chicago (73-51) picked up a game on the Pittsburgh Pirates (75-49), who lost at Miami, in the race for the first wild-card position in the National League. The Cubs trail the Pirates by two games.
Returning home after a 2-5 road trip, the Giants (66-59) lost for just the third time in their last 16 home games to fall 2 1/2 games behind the Los Angeles Dodgers (68-56), who won at Cincinnati, atop the NL West.
Schwarber belted a three-run shot in the third inning and Montero a two-run blast in the fourth as the Cubs built a 6-0 lead against Giants starter Matt Cain (2-4) and kept him winless in five starts this month.
Castro's home run followed an earlier single and double, giving him three-quarters of a cycle in his first three at-bats.
The replacement shortstop, subbing for Addison Russell, nearly completed the cycle in his only other plate appearance of the night, but was robbed of extra bases on a running catch by Giants right fielder Marlon Byrd leading off the eighth inning.
Castro finished with three of the Cubs' 10 hits and scored two of their eight runs. He was the only Chicago player to record more than one hit or one run scored.
Arrieta (16-6) became the first 16-game winner in the majors, breezing through six-plus innings en route to his 13th consecutive quality start. He allowed just an unearned run on four hits and one walk. He struck out six.
He left with an 8-1 lead one batter into the seventh inning.
The road win was his 10th of the year.
Arrieta also had a 2-0 win over the Giants earlier this month when the Cubs swept the Giants in a four-game series.
Still down by seven runs entering the eighth inning, the Giants rallied for four runs against the Chicago bullpen to pull within 8-5. Backup catcher Andrew Susac's two-out, three-run double highlighted the comeback attempt.
Right-hander Pedro Strop recorded the final out of the eighth with Susac on second base, and closer Hector Rondon worked a one-hit ninth for his 24th save.
Third baseman Matt Duffy had two of the Giants' nine hits.
Cain was pulled after allowing six runs and eight hits in five innings. He walked two and struck out three.
The veteran has failed to reach the sixth inning in four of his five starts in August, and has allowed four or more runs in five of his last six outings.
Cain retired the first six Cubs before Castro led off the third with a single.
Schwarber's home run -- a shot into the right-field pavilion -- came later in the inning after Castro was thrown out at home plate on center fielder Dexter Fowler's grounder to third that produced the second out. The rookie's 12th homer gave the Cubs a 3-0 lead.
Montero's 14th home run came one inning later and was a near-carbon copy of Schwarber's blast except that it scored only two runs for a 5-0 advantage.
The Cubs added a sixth run before inning's end on a double by Castro and an RBI single by second baseman Tommy La Stella.
Castro's homer -- a solo shot and his sixth of the season -- came in a two-run sixth inning off Giants reliever Yusmeiro Petit.
Arrieta scored the second run of the inning on an error by Giants shortstop Brandon Crawford to make it 8-0.
NOTES: Cubs manager Joe Maddon indicated before the game he would talk to pitching coach Chris Bosio about the possibility of pushing ace RHP Jake Arrieta up a day in the rotation in September so that he would be slotted to face the St. Louis Cardinals in two key series. At this point, Arrieta is not in line to pitch in either series. ... Chicago SS Addison Russell caught a late flight to San Francisco following the birth of his son and arrived on time to be available as a pinch hitter. ... The Cubs announced the signings of OF Quintin Berry and INF Emilio Bonifacio to minor league deals before the game. Both were assigned to Triple-A Iowa. ... Giants LHP Jeremy Affeldt went on the disabled list after he tore a patellar ligament in his left knee while enjoying a day off with his family at a lake near Spokane, Wash., on Monday. No surgery is scheduled. San Francisco recalled RHP Mike Broadway from Triple-A Sacramento.