BOSTON -- It was a brief stop in Boston for the A's, but they couldn't have been sad to leave Beantown in the rearview mirror.

Bizarre play marked this two-game series with the Red Sox, as the A's committed three errors that contributed to their 6-4 defeat Wednesday night before 37,006 at Fenway Park.

But the much more pressing concern is the loss of designated hitter Mike Piazza, expected to miss four to six weeks after spraining his right shoulder in a collision with Boston third baseman Mike Lowell as Piazza was running the bases in the sixth inning.

"It's frustrating," said Piazza, wearing a sling on his arm after the game. "I felt like I was starting to swing the bat better. It's a setback, but it is what it is."

With two outs in the sixth, Piazza was on second and broke for third on a grounder off the bat of Bobby Crosby. As Piazza dived for third base, Lowell looked like he might be headed for the bag to get a force, but he suddenly dived toward Piazza and tagged him out.

The two collided, and Piazza immediately grabbed his shoulder in pain as he lay on the ground. He was still clutching his shoulder as he headed for the dugout moments later.

Though Piazza thought his shoulder was separated, he wasn't terribly relieved to find out he sprained his AC joint.

"My whole arm went numb," he said. "When (the trainers) got out there, they thought it was a shoulder separation. This is the second-worst thing."

What next for these A's? They already were operating with right-handers Rich Harden and Esteban Loaiza, and outfielders Milton Bradley and Bobby Kielty all on the 15-day disabled list. They've also been without Mark Kotsay, on the 60-day disabled list, since early in spring training.

Nick Swisher is expected to return from a hamstring injury Friday to man center field, but right fielder Travis Buck was a late scratch Wednesday due to a sore right wrist.

"In spring training, there are 60 guys in that clubhouse, and the manager says everyone is going to contribute to the team," first baseman Dan Johnson said. "That's what it is. We still have guys capable of doing the job."

But in a lineup that has yet to produce a whole lot of pop, Piazza will be missed for the upcoming weeks.

He was signed to a one-year deal in the offseason to fill the cleanup role vacated by Frank Thomas after one season.

Though he had just one homer and eight RBI so far, his double helped key a game-winning rally Tuesday night. He was 2-for-3 before getting hurt Wednesday.

"Mike was swinging the bat well," assistant general manager David Forst said. "We're going to have to make up for his production."

The A's announced a trade after Wednesday's game, sending recently acquired Ryan Langerhans to the Washington Nationals for fellow outfielder Chris Snelling.

Asked the possibility of the team making another trade to find a big bat, Forst said the team would be active.

"We haven't had a lot of time to think about it," he said. "In the next 36 hours, we'll figure something out."

The A's jumped ahead of the Red Sox 3-2 on Wednesday on Johnson's two-out RBI single in the sixth. An inning earlier, Jason Kendall delivered a two-out, two-run single that pulled the A's into a 2-2 tie.

But shaky defense hurt the A's throughout the game. Langerhans, who played just two games with the A's after being dealt from Atlanta on Sunday, dropped a fly ball in center that led to Boston's second run in the fourth. Boston took the lead for good with two runs in the sixth to go up 4-3. An errant throw by Kendall on a rundown helped Boston go up 5-3 in the seventh, and they tacked on another run in the eighth when J.D. Drew's sinking liner skipped by right fielder Danny Putnam for a 6-3 lead.

Contact Joe Stiglich at jstiglich@cctimes.com.

RED SOX 6, A'S 4

  • NEXT GAME: Friday, at Devil Rays, 4:10 p.m.