No one saw this coming but the Oakland A's themselves. On Wednesday, Oakland became the first team to come from five or more games back to win a division or a pennant with fewer than 10 games to play, topping the Texas Rangers 12-5 to complete a three-game sweep and take the AL West crown. The A's never held sole possession of first place this season until they recorded the final out of game No. 162. "If there's ever a good day to do that, it's today," A's manager Bob Melvin said. Oakland is the fifth team in major league history to win a division or pennant after trailing by 13 games, which the A's did on June 30. It was sort of fitting that Oakland fell behind 5-1 in the third inning Wednesday, with the Rangers knocking rookie A.J. Griffin out after 2 2/3 innings. The A's romped back with six in the fourth; Coco Crisp tied the game with a double, and Texas center fielder Josh Hamilton dropped an easy flyball by Yoenis Cespedes to account for two more run and put the A's ahead 7-5. The Oakland bullpen turned in 6 1/3 scoreless innings, running its streak to 22 1/3 shutout innings to finish the regular season. Rookie Evan Scribner got the win with three scoreless innings, his second career victory. Before the season, the A's were projected to finish in last place in the West after trading away All-Star pitchers Gio Gonzalez, Trevor Cahill and Andrew Bailey. Instead, they rallied behind a rotation that ended the season filled with five rotations, a bullpen that rarely wavered and an offense that showed plenty of power in the second half. Oakland led the majors with 112 homers after the All-Star break. Next on the agenda, though, the A's must tackle the only team in baseball that enters the postseason with as much momentum as Oakland: the Detroit Tigers. Oakland opens the AL Division Series at Detroit on Saturday, when it will face Tigers ace Justin Verlander. Detroit charged past the Chicago White Sox in the season's final two weeks to claim the AL Central title. The Tigers' hard-throwing rotation, plus an offense led by Triple Crown winner Miguel Cabrera, will present a major challenge for the A's, but Oakland knows a little bit about overcoming low expectations.