"It just ups the ante a little bit," Embree said. "Their offense is tough on left-handers, so I knew I had my work cut out for me. I had a game plan, and I stuck to it."
Mark Ellis hit a go-ahead homer in the sixth inning, helping to send the defending AL champions to their fourth straight series loss.
"They're a fun team to play against," Ellis said. "To take two from them ... we know we have some talent on this team. We're probably underachieving a little bit."
The AL Central-leading Tigers, who began the day one game ahead of second-place Cleveland, dropped two straight to the A's after winning the series opener. The Tigers have lost six of seven games overall and eight of 10.
"We haven't done well lately. A lot of guys aren't hitting," Tigers manager Jim Leyland said. "When we've had some narrow leads, we've let those get away. Those are all combinations of things that add up to losing the game. You go through stretches, ups and downs, and you just have to grind them out."
Mike Piazza had two hits and drove in a run for the A's, who won their second straight following a four-game losing streak. Piazza is batting .354 (17-for-48) with 12 RBI since coming off the disabled list on July 20. He has six multihit games since then.
Andrew Brown (1-0) allowed two hits in 1 1/3 innings for his first major league win, and Embree got the five outs for his 12th save in 14 chances.
Brown allowed the single to Magglio Ordonez that drove in the game-tying run. Ellis' home run made him the winner.
"What the guys in the bullpen are doing is unbelievable," said Brown, who got the original scorecard as a souvenir. "It was fun to watch Alan pitch. We took two out of three from one of the best teams in baseball. It's awesome."
Oakland starter Dallas Braden, winless in 10 games since beating Baltimore on April 24, allowed two runs and four hits in 5 1/3 innings.
"I'm facing guys I grew up watching," Braden said. "Those guys are pretty potent. To come in and hold them to a low-run total; I'm happy."
Nate Robertson (6-9) gave up three runs and nine hits in six-plus innings. He lost his third straight start and is 2-6 in his last 10 starts.
Since shutting out Minnesota over seven innings on July 17, Robertson has allowed 15 runs and 30 hits in 17 2/3 innings for a 7.64 ERA. He's winless with a 7.11 ERA in three career starts in Oakland.
"We need to get on a roll here," Robertson said. "We need to turn this around. It seems like one little thing leads to bigger things every game for us."
Monroe's RBI single put the Tigers ahead in the second, put Oakland took a 2-1 lead in the third on consecutive doubles by Travis Buck and Shannon Stewart followed by Piazza's single. Ordonez's single made it 2-2 in the sixth.
Robertson retired nine straight batters before Ellis' 13th homer of the season, which matched a career high.
Oakland left the bases loaded in the seventh when Piazza and Ellis grounded into outs. After Detroit loaded the bases with one out in the eighth, Embree came in and retired Curtis Granderson on a short flyout to left, then struck out Monroe.
- Tigers SS Carlos Guillen , who was out of the starting lineup with a sore left knee, pinch hit in the ninth.
- A's RHP Esteban Loiaza pitched a rehab start with Triple-A Sacramento on Wednesday.
- Polanco's double extended the Tigers' streak of at least one extra base hit to 68 games.
- The A's finished with a 9-18 record in July, the second worst in the AL.
- Ellis has gone 67 games without making an error, three short of the Oakland mark set by Rafael Bournigal.
- The Tigers are 6-13 in games started by Robertson.
- Embree tied the Oakland record (with Rick Honeycutt in 1989) for saves by a left-hander.