BOSTON — Adam Kennedy homered on the first pitch of the game Wednesday night and the Oakland Athletics again outslugged Boston, winning 8-6 a day after beating the Red Sox with a 21-hit attack.

Brett Anderson (6-8) was staked to a 5-0 lead before even taking the mound and won at Fenway Park for the second time in 23 days. He beat the Red Sox 6-0 with a two-hit complete game on July 6.

Anderson had only one bad inning on Wednesday when he gave up a three-run homer in the first to Mike Lowell, who had five RBIs. He allowed just two singles in his other five innings.

On Tuesday, the Athletics overcame a 6-2 deficit after six innings and won 9-8 in 11. They had seven runs and 11 hits in the last five innings and ended that game with a .298 batting average in July, the second best in the majors. They outhit the Red Sox 10-9 Wednesday.

Oakland started with five runs and four hits in the first inning against Brad Penny (7-5).

Penny needed 37 pitches and 20 minutes to get out of the inning, striking out No. 9 hitter Eric Patterson.

After just nine pitches in the bottom of the first, the Athletics had a 1-0 lead and the bases loaded.

Kennedy followed up on his career-high five hits on Tuesday with his eighth homer of the season. Orlando Cabrera singled on Penny’s second pitch. On the fourth pitch, Kurt Suzuki singled. Then Jack Cust walked on five pitches.

Ryan Sweeney made the first out on a forceout at second on which Cabrera scored. A walk to Tommy Everidge reloaded the bases and Rajai Davis cleared them with a two-out double.

It was a rare case of wildness for Penny, who had walked just three batters in his previous five starts covering 28 1-3 innings.

The Red Sox scored single runs in the seventh, eighth and ninth and cut the lead to 8-6 on Lowell’s RBI single off Andrew Bailey, who then retired J.D. Drew on a groundout for his 13th save in 17 opportunities.

Boston had gotten back in the game in the first after Anderson hopped when he landed awkwardly on his fourth pitch. He took a few warmups, then walked Jacoby Ellsbury on the next pitch.

Kevin Youkilis also walked and Jason Bay struck out before Lowell homered over the left-field wall for his 11th homer, making it 5-3.

Anderson was sharp after that and finished with eight strikeouts while allowing four hits and four walks.

Penny also settled down with three hitless innings. But Suzuki led off the fifth with his sixth homer, also on the first pitch. Patterson doubled in the Athletics’ last two runs against Justin Masterson in the sixth.

Boston made it 8-4 in the seventh when Ellsbury tripled and scored on Dustin Pedroia’s groundout and 8-5 when Lowell hit a sacrifice fly in the eighth.

NOTES: Youkilis struck out four times and Bay fanned three times. … Suzuki has hit in all 21 of his games against Boston, an Oakland club record. He broke a tie with Ben Grieve, who hit in 20 consecutive games against Baltimore from 1999 to 2000, and Mitchell Page, who had a 20-game streak against Seattle from 1978-80. … Ellsbury had his sixth straight multihit game. … Boston lefty hitter Drew didn’t start against left-hander Anderson after going 3 for 5 Tuesday. Rocco Baldelli replaced him in right field but Drew pinch hit for him in the eighth against righty Brad Ziegler and singled.