OAKLAND, Calif. -- Conor Jackson fumbled through his locker and pulled out an unused baseball bat and ball, added his signature to both, then handed them over to Oakland Athletics' equipment manager Steve Vucinich.
That was a small price to pay for the veteran outfielder's first career grand slam, and Jackson was happy to oblige the fan who caught the historic hit.
"Obviously I'm not a 40-home run guy so those opportunities don't come too often," said Jackson, whose home run highlighted an eight-run first inning in Oakland's 9-1 win over the Los Angeles Angels on Sunday. "I'm going to savor it. It's exciting."
It was a monumental day all around for the A's, who broke out of a season-long offensive slump and set an Oakland record while taking three of four from their division rivals.
The nine runs matched the A's season high for scoring and marked only the fourth time this season they've had more than eight runs total.
Nearly all of the damage came in the first inning when Oakland sent 14 batters to the plate and chased Angels starter Joel Pineiro (5-4) after just one-third of an inning. Seven of the runs came before an out was recorded, a first for the A's in their history at the Coliseum.
"Since I've been here that's the best at-bats, consistent at-bats throughout the inning (we've had)," Oakland manager Bob Melvin said. "We took our walks and made them work. Conor's home run was kind of the cherry on top."
Hideki Matsui added a two-run single in the first and finished with three RBIs, while All-Star left-hander Gio Gonzalez (9-6) rebounded from his worst outing of the season and allowed four hits over seven innings to win for the third time in four starts.
Oakland went into the game as the second-lowest scoring team in the American League and had only 51 home runs -- second-fewest in the majors -- before Jackson's home run landed midway up the stands in left field.
It was Jackson's third homer of the season and the first grand slam by an A's player since Daric Barton had one against Seattle on Oct. 1, 2010.
That it came against Pineiro, whom he was only 2 for 12 against previously, made it that much sweeter for Jackson.
"That's a rarity for that guy," Jackson said. "I've never seen him like that before. Usually he's had my number quite a bit. He has a plus-slider, he just couldn't find it today. I'm looking to be aggressive right there with a good pitch and I got one."
Alberto Callaspo went 3 for 4 but the Angels, who went into the All-Star break trailing first-place Texas by one game in the AL West, didn't do much else and dropped four games back.
"We'll just turn the page on this one," Los Angeles manager Mike Scioscia said. "We don't need to spend much time dissecting this one. We need to get the pitching which will give us a chance to win, which we have been getting."
Pineiro was in trouble early on Sunday.
The Angels' right-hander never got comfortable and walked the first three batters he faced. Matsui's two-run single was Oakland's first hit of the inning, but Pineiro walked Scott Sizemore.
With the infield drawn in, David DeJesus hit a sharp grounder to first base but Mark Trumbo's throw home was wide of the plate, allowing Josh Willingham to score. Jackson then homered on an 0-1 pitch to clear the bases.
"It was weird, the ball was slipping out of my hand every time and on every pitch," Pineiro said. "I tried to do everything, look for sweat, dirt, rosin, maybe sneak one of our own balls out there. I tried everything."
Oakland made it 9-0 in the third when Matsui drove in Weeks, marking only the second time this season the A's have had nine runs in a game.
Gonzalez did the rest while helping Oakland take three of four from its division rival. The A's lone representative at the All-Star game, Gonzalez recorded his first six outs by strikeout and only allowed two runners to reach second base. He finished with eight strikeouts.
"It's just fun to see the team have a little life in there," Gonzalez said. "We came out strong and right off the bat we went out there swinging the bat. To take three of four wasn't easy."
Los Angeles had hoped to use the series with Oakland to build momentum for a critical three-game stretch at home against Texas beginning Tuesday.
After losing to the A's for the eighth time in 13 games this season, however, the Angels face an uphill battle against the streaking Rangers.
Pineiro's one-third of an inning is his shortest as a starter. ... The Angels hadn't allowed eight runs or more in the first inning since Sept. 3, 2000. ... Matsui's three RBIs are a season high. ... Entertainer MC Hammer threw out the ceremonial first pitch and was honored with his own bobblehead doll. It was part of Oakland's '80s throwback day which included former pop star Taylor Dayne singing the national anthem.