"This showed the character of this team," Red Sox second baseman Dustin Pedroia said. "We're not giving up for anything. That was awesome."
Pedroia took advantage of the extra inning to extend his hitting streak to 14 games after going hitless in his first four at-bats.
A's third baseman Eric Chavez, who had 27 hours to rest between Sunday afternoon and Monday night, finally settled things with a two-out solo home run in the bottom of the 11th inning, giving the A's a victory in the opener of a four-game set.
Kyle Snyder (1-1) watched his 1-1 delivery sail over the right-field fence.
"I left the ball up right over the plate," Snyder said. "He's a good hitter and he'll take advantage of balls like that.
Wily Mo Pena was a late addition to the Boston lineup because of a stomach ailment to Coco Crisp and he's a big reason why the Red Sox kept playing past the ninth.
The ninth inning could become a battle cry for the Red Sox, as in "Remember the ninth!" The Sox were two runs down and had managed a mere four hits, which included solo shots by Pena and David Ortiz.
Ortiz led off the ninth with a double. Two outs later he was still standing on the field. Jason Varitek drove him home with a pinch-hit single. Crisp went in to run for him.
Pena singled home Crisp, who was running from first on the pitch, and the game was tied at 4.
"Crisp is the only guy we had who scores on that play," Francona said. "He didn't have the flu but he was struggling before the game."
Joel Pineiro, in his second inning of work, walked Travis Buck to open the bottom of the ninth and gave up a broken-bat single to Nick Swisher, which allowed Buck to reach third.
J.C. Romero was called in to try to work out of trouble. He walked Dan Johnson to load the bases but then struck out Chavez before inducing Bobby Crosby's double-play ball that ended the threat.
"I'm not really thinking about that right now," Romero said. "It was a tough loss. We battled hard but we came up short."
Despite the late rally, the Red Sox could not avoid their third two-game losing streak of the season. The Red Sox have lost four of their last five games. They have not suffered a three-game losing streak yet.
"That just shows the resilience this team has," said Snyder. "But a loss is a loss. It doesn't matter what course of events lead up to it."
Julian Tavarez gave Boston 5 2/3 pretty good innings and he's not usually that effective in Oakland. He's allowed nine runs in his seven previous innings here.
Brendan Donnelly gave the Red Sox 1 1/3 terrific innings of relief to keep things close.
"We came back late in the game, like always," Tavarez said. "I was more rested than most of the guys. They were looking for their rooms at 4:30 in the morning. It was a tough couple of nights with a long flight and we still played good baseball."
Ortiz ended his longest homerless drought as a Red Sox when he took A's starter Dan Haren deep on a 3-2 pitch with two outs in the first. He had gone 19 games and 69 at bats since his last homer on May 9.
"It's tough," Ortiz said. "I'm surprised we had these games like this. Hopefully they will fix it up."
Pedroia, the AL Rookie of the Month, was thrown out at the plate in the top of the 10th trying to score on an Ortiz double.
"It was the right play," Pedroia said. "They just made a great relay. I didn't have much of a lead at first and I was out by 10 feet. I didn't know what to do. I was freaked out I was out by so much."
Oakland second baseman Mark Ellis also took advantage of his extra at-bat to complete hitting for the cycle. He tripled home two runs in the second, hit a solo homer in the fourth, doubled in the sixth and singled in the 10th.
Cleveland's Andre Thornton was the last opponent to hit for the cycle against the Red Sox -- on April 22, 1978.