SAN FRANCISCO -- Pittsburgh Pirates star Andrew McCutchen likes the direction his team's offense is taking lately.

At AT&T Park the past three seasons, that direction often has been out of the ballpark.

McCutchen and Jordy Mercer hit three-run home runs, and Gerrit Cole continued his impressive pitching in his home state, helping the Pirates bomb the San Francisco Giants 10-3 in the opener of a three-game series Monday night.

Winning for the seventh time in their past nine games, the Pirates scored six runs in the first two innings, during which Giants manager Bruce Bochy was ejected.

"There was some frustration really all night," Bochy said of his 72nd career ejection, his second this season. "I don't think (plate umpire Chris Conroy) had a real good night, to be honest as far as consistency. But that really had nothing to do with what happened tonight. We gave up three-run homers."

Conroy's strike zone and the Giants' seventh loss in 11 games since the All-Star break also took its toll on San Francisco pitching coach Dave Righetti, who got tossed in the ninth inning.

McCutchen drove in four runs, including three on a two-out homer that capped a four-run second inning against Matt Cain (3-9).

McCutchen already had contributed a run-scoring infield out to a two-run first inning as the Pirates built a 6-0 lead.

"It's the guys in front of me," McCutchen said of the fact that he has driven in 12 runs in his past seven games in San Francisco. "They give me the opportunity to drive them in, and I can cut loose."

Mercer's homer came off Giants left-hander Josh Osich in a game-clinching eighth inning after San Francisco had closed within 6-3. It was Mercer's third hit of the game.

"Everyone's showing up," McCutchen said after watching a 14-hit Pittsburgh attack that featured hits from eight different players. "This offense is good. We've shown that. We can be a real good team if we do that more consistently."

Cole (8-7) went six innings, allowing two runs and six hits. He walked four and struck out four. The win improved the UCLA product's record to 7-2 in nine career major league starts in California.

"A real professional effort," Pirates manager Clint Hurdle said, noting Conroy's strike zone affected both starters. "It was a hard night. He had a tough zone. But when (Cole) needed to make pitches, he did."

Josh Bell collected three hits, and Josh Harrison and David Freese added two apiece for the Pirates, who won their seventh straight game in San Francisco.

The Giants swept a three-game series in Pittsburgh earlier this season.

Buster Posey drove in two runs and Brandon Crawford one as the Giants scored single runs in the fourth, fifth and seventh innings to climb within 6-3.

Posey, Crawford and Eduardo Nunez had two hits apiece for San Francisco, which fell to 3-5 on its 10-game homestand.

Cain was charged with six runs, just two of which were earned, in four innings. He struck out one and walked one.

"We both exchanged a little words," Cain said of his displeasure with Conroy. "I was a little bit behind in the count on some of the guys. In the first couple of innings, I was kind of around the zone instead of attacking the zone like I should have been."

McCutchen's homer gave the Pirates a 6-0 lead in the second inning and triggered a chain of events that got Bochy tossed.

Cain, unhappy with the work of Conroy basically from the first pitch, vented his frustration of the McCutchen homer loudly upon the umpire.

Bochy quickly jumped into the middle of it, sacrificing himself to save his pitcher.

NOTES: The Pirates have won 11 consecutive games in which they have scored at least four runs. ... The home runs by CF Andrew McCutchen and SS Jordy Mercer were the Pirates' 10th and 11th in their past nine games at AT&T Park. Pittsburgh has hit at least one homer in six straight games in San Francisco. ... Giants pitching coach Dave Righetti's ejection was his fourth as a coach. ... San Francisco SS Brandon Crawford's two hits in three at-bats against Pirates RHP Gerrit Cole improved his career average to .222 (4-for-18) against his brother-in-law. ... RHP Matt Cain extended his winless streak to 11 starts, the longest run by a Giant since Cain went 15 starts without a win bridging the 2015 and 2016 seasons. ... The game was played on the 53rd birthday of LF Barry Bonds, a former star for both the Pirates and Giants. Bonds did not attend the game.