But the biggest bummer was the loss of designated hitter Mike Piazza, whose two hits in three at-bats raised his batting average to .391 (9-for-23) over his past six games and contributed to the rallies that gave starter Chad Gaudin the lead he handed off to the 'pen.
Oakland's cleanup hitter and the club's leading hitter (.291) among regulars who hadn't been on the disabled list suffered a sprained AC joint in his right shoulder during a sixth-inning collision at third base and will join No. 3 hitter Milton Bradley on the DL.
Piazza was told he'll be out four to six weeks.
"It's really frustrating," Piazza said while wearing a sling in the quiet A's clubhouse. "I felt like I was starting to swing the bat better. It's a tough setback."
Manager Bob Geren called it a "big injury."
"Obviously, it's not good for us," Geren added. "But we'll do our best and keep fighting every day."
According to A's assistant general manager David Forst, the team will look into making a deal to compensate for the loss of Piazza, who was signed to a one-year, $8.5 million deal over the winter.
"We haven't had much time to think about it," Forst said. "In the next 36 hours, we'll figure something out."
Piazza's replacement on Wednesday was Nick Swisher, who had missed the previous six games with a strained hamstring and looked awfully gimpy while hitting into an inning-ending double play in the eighth.
"I told him to do that," Geren said of Swisher's cruise-control job to first base. "We were trying to take a shot there [and get] either a walk or a big extra-base hit, then have [Travis] Buck pinch-run for Nick."
Much as they did against Joe Blanton in Tuesday's series opener, the Red Sox took an early lead on the strength -- or lack thereof -- of some well-placed hits and some sloppy defensive play by the A's.
In the third, Julio Lugo drew a leadoff walk, stole second, took third on an infield single and scored on a groundout. An inning later, new center fielder Ryan Langerhans couldn't handle a looping liner hit directly at him by Coco Crisp for a two-base error. Crisp scored on a single to center by Lugo.
"I got the glove between my eyes and the ball," explained Langerhans, who was acquired from the Braves on Monday and traded to the Nationals after Wednesday's game. "That's something, as an outfielder, you don't want to do."
The A's put together a more traditional rally in the fifth. Piazza led off with a single to break up Red Sox starter Josh Beckett's no-hit bid, Dan Johnson followed with a double and Jason Kendall's two-run single to center with two out tied it up.
Having relieved Beckett of his aura of dominance, Oakland took the lead in the sixth, but it was costly. After Shannon Stewart led off with a single, took second on a two-out single by Piazza and scored on a single to right by Johnson, Red Sox third baseman Mike Lowell fielded a grounder by Bobby Crosby and beat Piazza to the bag with a dive that ended in a nasty collision that left Piazza writhing in pain for several minutes before being he was led into the clubhouse.
"It just kind of felt like he kind of flopped on me," Piazza said, adding that he initially feared he'd separated the shoulder. "My whole arm went numb. It was just a freak play.
"It's really painful right now."
Boston chased Gaudin with Jason Varitek's leadoff single in the bottom of the sixth, and the Red Sox took the lead against lefty reliever Jay Marshall, who was greeted by a double by Crisp that bounced over third baseman Eric Chavez's head. Alex Cora tied it up with an RBI groundout, after which Lugo lofted a sacrifice fly to right field.
An unearned run padded the lead in the bottom of the seventh, which Lowell opened with a single off righty Kiko Calero. Lowell, who found himself hung up between first and second when the A's pitched out on a hit-and-run, reached second when Kendall bounced his throw to the bag, then scored when Cora greeted lefty Alan Embree with an RBI single.
Rookie right fielder Danny Putnam committed error No. 3 of the night for the A's in the eighth, letting a single by J.D. Drew slip under his glove as Kevin Youkilis scampered home to make it 6-3.
Pinch-hitter Todd Walker closed the scoring with an RBI single in the top of the ninth.
Geren tried to put a positive spin on the two-game split, but his perennially half-full glass seemed closer to empty when he was asked about his team's defense.
"I have other things on my mind right now, to be honest," he said.