SAN FRANCISCO -- Baltimore Orioles rookie Dylan Bundy had a bunch of new experiences in his interleague debut Friday night.

But in the end, one thing was happily familiar: The win.

Bundy recorded his third consecutive victory with 5 2/3 strong innings and Mark Trumbo belted his major-league-leading 33rd home run, propelling the Orioles to a 5-2 triumph over the San Francisco Giants in the opener of a three-game series.

Chris Davis also homered for the Orioles (65-50), who reclaimed first place in the American League East from the Toronto Blue Jays (65-51), who lost 5-3 to Houston.

"We did a lot of good things tonight," Orioles manager Buck Showalter assured of his club's second consecutive win after three straight losses. "Dylan did a real nice job."

The loss was San Francisco's 17th in 25 games since the All-Star break, but the Giants (65-50) nonetheless were able to retain a one-game lead in the National League West after the Los Angeles Dodgers (64-51) lost to Pittsburgh.

"We have to get this offense going," assessed Giants manager Bruce Bochy, whose team has alternated wins and losses in their last seven outings, totaling just four runs in the four losses. "We did run into a hot pitcher. But we still have to get these bats clicking."

The homers by Trumbo and Davis came off Giants starter Matt Cain, who entered the game on a three-game winning streak but couldn't get out of the fifth inning.

Trumbo's blast, one of the longest at AT&T Park this season at an estimated 441 feet, followed a leadoff single by Manny Machado in the third inning, giving the Orioles a 4-0 lead.

"He threw me a lot of tough pitches," observed Trumbo, who had fouled off four consecutive pitches before concluding the nine-pitch at-bat with the homer. "I finally got one I could handle."

Davis connected for his 24th leading off the fifth, pushing the Baltimore lead to 5-1 and ending the night for Cain (4-7).

"That's an excellent ballclub over there. They don't beat themselves," Trumbo praised of the Giants. "It was nice to get a bit of a cushion on them."

The home runs increased Baltimore's season total to 174, the best in baseball.

The Giants have allowed 37 home runs in their 25 games since the All-Star break, the most in the NL.

Bundy (6-3) limited the Giants to three hits before being pulled after his 92nd pitch with two outs and nobody aboard in the sixth inning. He allowed one run, walking two and striking out three.

The former No. 4 overall pick in the draft lowered his season ERA to 2.93 in the coldest weather he's pitched in this season (59 degrees at first pitch) and against a team wearing Orioles colors (orange and black).

"I don't want to blame the weather," Bundy said of the fact that he basically had just one pitching going well, his fastball. "Great ballpark. Great crowd ... Good day."

Bundy assured he understands the Orioles' philosophy to limit his pitches relatively early in the season. He was making just his sixth start.

"I wanted to go six (innings). That's your goal," he said. "Or keep the team in the game. I felt I did a decent job of that."

Bundy also batted for the first time in his career (two strikeouts and a grounder back to the mound).

"That wasn't pretty," he critiqued.

Mychal Givens and Donnie Hart retained Baltimore's 5-1 lead through the eighth inning with 2 1/3 innings of hitless relief before the Giants got to Brad Brach for a ninth-inning run on a single by Angel Pagan, a wild pitch and an RBI single by Brandon Belt.

With the lead cut to 5-2, closer Zach Britton came on to retire three straight batters, striking out Buster Posey and Hunter Pence, for his 36th save.

"The scouting report is out on him," Trumbo said of Britton, who has no blown saves this season. "It doesn't matter. There's not much you can do."

All eight position players had hits for the Orioles, who took a 7-6 lead over the Giants in the all-time series. Davis, Machado and Adam Jones had two hits apiece.

The Orioles improved to 7-4 in interleague play this season.

Pence and Denard Span had doubles for the Giants, who were opening a 10-game homestand.

The Giants have lost the opener in eight of their last nine series.

"We have the ability to get on a good streak. That's the way we got to look at it," observed Giants catcher Buster Posey. "We have to look and say tomorrow is the day we get it going."

George Kontos and Jake Peavy combined for five hitless innings of relief for the Giants, who fell to 7-11 in interleague play.

Cain, who had not allowed a run in either of his previous two starts over a stretch of 10 innings, recorded only four outs before the Orioles got on the board thanks to consecutive doubles by Jonathan Schoop and Matt Wieters in the second inning.

Jones' two-out single scored Wieters with a second run in the inning.

Cain was pulled one batter into the fifth, having allowed the home runs to Trumbo, a two-run shot in the third, and Davis, a solo blast leading off the fifth.

He gave up hits to 11 of the 23 batters he faced and a total of five runs in four-plus innings. He walked one and struck out seven.

"It's fair to say he didn't have his good fastball command," Bochy said of Cain. "They're a good hitting ballclub with a lot of power. They took advantage of him."

Down 3-0, the Giants put up a run in their half of the third on an RBI double by Span that scored Joe Panik, who had singled.

NOTES: The save was LHP Zach Britton's 40th straight dating back to last season. ... The 11 hits allowed by Giants RHP Matt Cain equaled his career high. ... Friday's interleague matchup was the 13th between Baltimore and San Francisco. Ten of the games have been played at AT&T Park. ... The Orioles began the series having recorded quality starts in seven consecutive games, but the streak ended when RHP Dylan Bundy came one out shy of the required six innings. Not that the Orioles were close to sniffing the club record: a 20-game run from Aug. 3-22, 1961. ... Baltimore RHP Darren O'Day flew back to Baltimore before the game to have his ailing right shoulder examined. The Orioles hope he can rejoin the team for its home series against Boston that begins Tuesday.