BOSTON -- Jonathan Papelbon was almost unhittable in April. The beginning of May was much different.
Boston's dominant closer allowed a tying, two-run homer to Travis Buck in the ninth inning, his first blown save in nine opportunities, and the Oakland Athletics beat the Red Sox 5-4 in 10 innings Tuesday night.
"You're not going to win them all," Papelbon said, although it might have seemed that way to fans used to watching him. "I'll take that loss on my back and I'll pick up the team again when they need me."
Papelbon threw 35 pitches in just one inning and allowed three hits after giving up two hits and no runs in his other 9 1/3 innings this season. As a rookie last year, he had 35 saves and a 0.92 ERA. But on Tuesday his best two pitches, a fastball and splitter, were ineffective.
Buck's third homer of the season followed a leadoff single by Bobby Crosby.
"I tried to elevate (the ball) and left it right over the middle," Papelbon said. "That's the frustrating part about it. You got a guy 0-2 and he tomahawks a home run out of the park, but you have to live and learn."
Buck said he saw right fielder Eric Hinske drifting back as the ball sailed toward the wall.
"It had enough to get out," Buck said. "Once Bobby got on in the ninth, we were one swing away."
Dan Johnson, who hit a solo homer in the fourth, doubled in the winning run with no outs in the 10th off Brendan Donnelly (0-1). It followed a leadoff double by Mike Piazza. Huston Street worked a perfect ninth for his seventh save in eight chances.
"I threw a bad pitch to Piazza," said Donnelly, who was 9-0 since his last loss on Aug. 12, 2005. "They jumped on me immediately and before I knew what was going on, boom, we were losing the game."
The Red Sox had won four of five games and began the day with the best record in baseball but wasted another strong start by Curt Schilling, who allowed two runs in seven innings.
"To get runs off pitchers of that caliber is a boost," said Oakland manager Bob Geren, who was ejected in the fifth for arguing a strikeout call, "especially when we've been struggling to score runs."
The Athletics began the game with the second worst batting average in the majors but had 13 hits. Justin Duchscherer (2-1) got the win, Oakland's second in six games. Boston had runners at second and third with two outs in the ninth against him, but Coco Crisp grounded out to first.
"The second half of the game, we upped our enthusiasm," Piazza said. "We believed we could win instead of rolling over after skipper was kicked out of the game."
Neither Papelbon nor Donnelly had allowed a run before Tuesday.
"Our bullpen has been phenomenal," Schilling said. "It doesn't always work out the way you want it to."
Papelbon pitched after Hideki Okajima pitched the eighth, his 12th consecutive scoreless outing.
"We all get used to (Papelbon) being almost perfect," Boston manager Terry Francona said. "At some point, you're going to give up runs."
Boston took a 3-0 lead in the first off Joe Blanton, just the second time in 26 games this season that Oakland allowed a run in that inning.
The first run scored on a sacrifice fly by Manny Ramirez. Kevin Youkilis then singled David Ortiz to third and stole second. Ortiz scored on Mike Lowell's single to shortstop Crosby and Youkilis came in when Crosby threw to third baseman Eric Chavez instead of to home.
Youkilis made it 4-0 on a sacrifice fly in the third before Johnson's first homer of the year.
The Athletics scored a run in the seventh and nearly had more. Buck doubled and took third on Jason Kendall's single. Todd Walker lined a sinking liner to center that Crisp charged and made a diving catch on. Buck scored on the sacrifice fly, but Crisp's catch kept Walker off base and Schilling retired the last two batters.
- Ramirez's single in the eighth was his 1,000th hit with Boston, making him the 14th player to do that with two teams. He had 1,086 with Cleveland.
- Geren was ejected for the first time this season when he argued a swinging third strike call by home plate umpire Charlie Reliford against Chavez with two outs and runners at second and third in the fifth. The runner at second, Mark Ellis, reached that base with a hard grounder down the third-base line that the ball boy, thinking it was foul, fielded. Jason Kendall, who was on first, had to stop at third.
- Boston rookie 2B Dustin Pedroia went 0-for-3 and is in a 5-for-48 slump.