Breakout seasons from Jarrod Parker, Josh Donaldson and Jed Lowrie have helped the A's repeat as surprise contenders.
As ESPN's Jerry Crasnick said, September is the best time for baseball. A's fans can look forward to the home stretch, where 20 of the 22 remaining games are against teams with losing records.
The A's go from battling the AL West's best to the sorry Lastros, who will spend September 5-8 fighting at O.Co Coliseum.
Third baseman Brett Wallace, first baseman Chris Carter and catcher Max Stassi all played for the A's minor league affiliates. Carter leads the Astros with 27 home runs, but sports an ugly .217 batting average.
Thursday night's game featured Sonny Gray against another former Athletics farmhand, Brad Peacock. Peacock has struggled to a 5.62 ERA and 1.45 WHIP, but didn't allow a run until the eighth inning in Houston's 3-2 win.
The A's face rookie Brett Oberholtzer on Saturday, who is 4-1 with a 2.79 ERA and 1.06 WHIP in his first six starts. Oberholtzer outdueled Hisashi Iwakuma last week, and will be the A's toughest test over the weekend.
At 47-93, the Astros are the only MLB team without 50 wins this season. Oakland is 12-5 against the 'Stros, and will be looking for an easy series win.
The A's hit the road for Minneapolis after the Houston series, then host the Twins from September 19-22.
While the Twins are well under .500 and recently lost Justin Morneau, the roster has some talent. Second baseman Brian Dozier has 17 home runs, while Glen Perkins has 32 saves in 36 chances.
Problem is, Perkins is essentially useless if Minnesota's starting pitchers get shelled early in the game. Recent call-up Andrew Albers is the only starter with an ERA under 4.00.
The Twins have won four of their last six games, two of which were against the Rangers. The A's can't afford to underestimate their opponents, especially if Joe Mauer returns soon.
The rival Rangers are the A's only remaining opponent with a winning record. As both teams attempt to avoid the unpredictability of a wild-card spot, the September 13-15 series could have a major impact.
Texas is 9-7 against the A's this season, but Oakland took two of three in the last series. If players like Brandon Moss, Coco Crisp and Daric Barton stay hot, the A's will crush the ball all over Rangers Ballpark in Arlington.
The A's pounded a combined six home runs in the first and last games of the recent series, but managed just one run against Martin Perez in Game 2.
Facing four contenders in a row could drop the Rangers deep into second place, and the A's have a chance to bury them in the Texas dirt. A sweep could give the A's a firm hold on the division.
Diehard A's fans remember going into the last series of the 2004 season tied with the Angels for first place, only to watch in horror as Anaheim took the first two games thanks in part to a fella named Bartolo Colon.
Oakland hosts the Angels from September 16-18. After a three-game series against the Twins, the A's head south for a rematch in Anaheim.
The Angels have offensive stars like Mike Trout, Mark Trumbo and Howie Kendrick, but the A's pitching and depth has been better over the last two years. Oakland went 10-9 against the Halos in 2012 and is 8-2 this season.
The A's went 12-7 against Seattle in 2012, including a 7-0 run to end the season. The dominance hasn't carried over to this season, as Oakland has lost every series after the opening four-game split.
The two teams face off again in the final days of the season, when the A's are likely to be fighting for the division.
Relievers Jerry Blevins, Sean Doolittle and Grant Balfour need to iron out their kinks before playing the Mariners. The A's don't want to give up another walk-off like the highlight on the right.
If the Mariners' current rotation holds up, Felix Hernandez will start the first game against Dan Straily. The game's 7:05 PM start time is bad news for Straily, who has a 2.63 ERA during day games and a 5.21 mark at night.
Oakland aces Bartolo Colon and Jarrod Parker will finish the year against Erasmo Ramirez and Taijuan Walker. Both Mariners starters are inexperienced, but Walker is considered the No. 5 prospect in baseball and Ramirez has a 2.81 ERA in his last four games.