OAKLAND, Calif. -- For a team that's spent most of the season atop the American League standings and recently ran off seven straight wins, the Houston Astros suddenly look a little vulnerable.
Back-to-back meltdowns by their bullpen and an offense that managed only five runs in 18 innings against struggling Oakland resulted in a doubleheader sweep for the Athletics.
Normally reliable Houston reliever Chris Devenski allowed two runs in the seventh inning, including Chad Pinder's tiebreaking homer with two outs, and the Astros lost the second game 11-4 on Saturday.
Houston's third straight loss to the last-place A's dropped the Astros into a tie with streaking Cleveland for the best record in the AL at 86-56 -- the first time they haven't had sole possession of the top spot since May 10. The Indians have won 17 straight.
"Really just not making pitches," said manager A.J. Hinch, whose bullpen has been roughed up for 23 runs over 10 1/3 innings in this series. "They were good for a really long time. They're going to be good again, but not today."
The Astros' magic number for winning the AL West dropped to seven when the Angels lost in Seattle.
Houston lost the first game 11-1 when Astros pitchers forced in five runs with bases-loaded walks and the team tied a franchise record with 13 free passes.
The nightcap wasn't much better.
Jose Altuve hit his 23rd home run and inched closer to 200 hits, but the Astros couldn't hold an early three-run lead in the makeup of an April 16 rainout -- the first at the Coliseum since 2014.
Devenski (8-4) had allowed one earned run over his previous 15 appearances before getting touched up for two in the seventh.
The Astros' bullpen gave up nine runs overall and spoiled a mostly strong outing by starter Brad Peacock, who struck out nine. He allowed two runs and didn't walk a batter over 5 2/3 innings.
"Definitely not our best, but we'll put it behind us and move forward," Devenski said. "That's all we can do right now. We have a great team. Tomorrow's a new day and we'll start fresh."
Pinder homered again as part of a six-run eighth for Oakland, which has won four straight overall.
Chris Hatcher (1-1) retired six batters for the win.
In the opener, Oakland led 3-1 before Tyler Clippard issued the first bases-loaded walk to Jed Lowrie in the sixth inning. Reymin Guduan forced in three more while allowing five straight walks on 28 pitches in the eighth. Astros infielder J.D. Davis relieved Guduan and struck out Marcus Semien and Khris Davis, but also allowed another run by walking Pinder.
Houston tied the club mark for walks set on May 4, 1975, against San Francisco.
The Astros entered the series with a seven-game winning streak.
"It's coming down to it," losing pitcher Charlie Morton said. "I think we really just want to finish the year going in the playoffs on our own streak, get in a groove and continue on in October."
Morton (11-7) allowed three runs in five innings.
Daniel Gossett (4-8) had a career-high seven strikeouts and allowed one run over six-plus innings for his first win since Aug. 2.
"Maybe not his best command at times, got behind some guys, but made some big pitches when he had to," manager Bob Melvin said.
Khris Davis hit a two-run single in the sixth, giving him 101 RBI this season after he drove in 102 runs last year. He is the first A's player to have 100 RBI in back-to-back seasons since Eric Chavez and Miguel Tejada from 2002-03.
Astros catcher Juan Centeno was being examined for a concussion after being hit in the head by Lowrie's bat on a follow-through in the second inning of the first game. Max Stassi replaced Centeno. ... Evan Gattis was activated off the disabled list after being out due to soreness in his right wrist and is scheduled to be the DH on Sunday. The veteran catcher went on the DL five days after coming off following a three-week stint due to a concussion.
LHP Dallas Keuchel (12-3, 2.88 ERA) pitches the series finale for the Astros on Sunday, while the A's counter with RHP Kendall Graveman (4-4, 4.70). Keuchel is 3-0 with a 0.83 ERA in three starts against Oakland this season.
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