OAKLAND, Calif. -- To one, it was the WBC and soreness. To the other, nothing much was wrong.

It appeared, after last night's 6-5 loss in 12 innings to the A's in Oakland, that the manager and the pitcher had differing views about what exactly was the issue with Daisuke Matsuzaka. Just one inning and 43 pitches into the game, his night was over and the night for the bullpen had just begun.

He left the mound, was patted on the back, and headed into the tunnel after barely making a dent on the game -- but giving up five runs to the A's. It was later announced in the press box by a Red Sox spokesperson that Matsuzaka had left with arm fatigue. But, to him, that wasn't quite the case.

"It was a similar result to last time and I feel very apologetic," Matsuzaka said, through interpreter Masa Hoshino, when asked about the game.

Then asked, directly, about the fact that he might be experiencing physical issues, Matsuzaka said, "Not in particular."

Pressed again about comments by Terry Francona that Matsuzaka was feeling soreness, the pitcher said, "I haven't had the chance to speak with the manager yet after the game ended, but for me personally I think that I'm OK physically."

"He didn't communicate too much," Francona said, of Matsuzaka. "We talked to him the other day because he expressed a couple days ago some kind of general soreness or fatigue in the back of his shoulder from the WBC. We thought we talked it through pretty good in Anaheim and he came out tonight and didn't really have a whole lot. We'll re-evaluate him in the morning."

From the manager's comments, it was clear that he placed the blame on the World Baseball Classic, in which Matsuzaka pitched for Team Japan. He spent just one week in Red Sox spring training camp before the season started after being named the MVP of the WBC for the second straight time. He then pitched last Thursday against the Rays -- unsuccessfully -- giving up four runs on nine hits and three walks in 5 1/3 innings.

"Came out of the WBC and felt like he had ramped up too quick, all the things we worry about," Francona said. "Then he threw his bullpen [in Anaheim] and assured us he was fine.

"I'm going to have to take some blame there because, after talking to him, I thought that we were in pretty good shape. So if anybody needs to shoulder some blame, it would be me."

Because last night was a disaster. Matsuzaka had thrown 13 pitches before recording an out, allowing a single to Ryan Sweeney and a walk to Orlando Cabrera before Jason Giambi flied out to left. Then Matt Holliday hit a two-RBI double to center, Jack Cust hit an RBI single, and Nomar Garciaparra walked. Kurt Suzuki flied out to right, followed by RBI singles from Travis Buck and Mark Ellis. Ryan Sweeney hit a ball to first base for the final out of the inning, and of the night for Matsuzaka.

This is not the first time the Sox have had a pitcher come back from the WBC and experience arm fatigue. Mike Timlin had the same problem after the inaugural competition in 2006.

"He's tested real well the whole time strength-wise and that's been very encouraging," Francona said. "I know I'm harping on it a little bit, but I think he probably tried to ramp up too quick and we're feeling the effects of it. We're eight games into the season and we've lost some games. It's not a real fun night."

While no decisions had been made on Matsuzaka last night, the Sox will be extremely short in their bullpen for the finale against the A's, though the team does have a day off following the trip home to Boston. Every reliever, other than Takashi Saito, was used in last night's game. Justin Masterson threw four innings. Hideki Okajima threw two. Manny Delcarmen and Ramon Ramirez each got more than three outs.

But the Sox did not divulge last night whether Matsuzaka will need to go on the disabled list with the arm fatigue. That news could come this morning, as the Sox take on the A's in an attempt to salvage one game of the three-game series.