"We've just gone out and played well," Cardinals manager Mike Matheny said. "We have to do the same thing tomorrow, or else we'll get embarrassed. You can't take any team, anybody for granted for a second."
The Nationals and Reds are also in a battle for home-field advantage. With Washington falling to Philadelphia, 6-3, and Cincinnati beating Milwaukee, 4-2, both teams are tied for the best record in the NL.
In the AL Central, it's an eight-game season after the Tigers' 2-0 victory over the Royals, powered by Anibal Sanchez's three-hit shutout. That moved Detroit into a tie with the White Sox, who had lost earlier in the day to Cleveland, 4-3.
"It is what it is," Detroit manager Jim Leyland said. "Then there was eight. We thought all along it was going to be a dogfight, and it is."
The AL Wild Card also saw plenty of drama with all three teams in the hunt winning pivotal games on Tuesday.
Left for dead last week, Tampa Bay has ridden a six-game winning streak right back into contention. AL Cy Young Award candidate David Price tossed a complete game in the Rays' 5-2 win over Boston, which kept them three back of Oakland.
"It should be real. It's real to me right now. I'd like to believe the players believe it's real," manager Joe Maddon said of a potential comeback. "Listen, we just keep going 1-0, we're in pretty good shape. You got to keep applying pressure."
The A's responded to that pressure on Tuesday with a 3-2 victory over Texas in 10 innings. George Kottaras' solo homer off reliever Mark Lowe proved to be the difference.
To close out the night, the Angels kept pace with Oakland by hanging on for a 5-4 victory over Seattle. They remain two games back.
Wednesday's key games to watch (all times ET)
Yankees (Sabathia, 13-6) at Twins (Deduno, 6-5), 1:10 p.m. Preview >
The Yankees look to put pressure on Baltimore -- which plays a night game -- by expanding their AL East lead of 1 1/2 games as CC Sabathia takes the hill in Minnesota.
Dodgers (Harang, 9-10) at Padres (Richard, 14-12), 6:35 p.m. Preview >
Los Angeles is hanging by a thread in the NL Wild Card hunt, 4 1/2 games behind the Cardinals. It sends Aaron Harang to the mound against his former club.
Royals (Guthrie, 7-12) at Tigers (Porcello, 9-12), 7:05 p.m. Preview >
Detroit hasn't held sole possession of first place in the AL Central since July 23. It could earn that with a win and a White Sox loss.
Nationals (Lannan, 3-0) at Phillies (Kendrick, 10-11), 7:05 p.m. Preview >
The Nats are in a battle with Cincinnati for the top seed in the NL. This year that could be more important than ever with the winner facing a team coming off a Wild Card game that will tax its staff.
Blue Jays (Villanueva, 7-6) at Orioles (Gonzalez, 7-4), 7:05 p.m. Preview >
Baltimore appears to be in good position for a playoff berth, but what the O's are after is a division crown -- for which they trail the Yankees by 1 1/2 games.
Marlins (Johnson, 8-13) at Braves (Maholm, 12-10), 7:05 p.m. Preview >
The Braves clinched a playof berth on Tuesday, but, mathematically, they still have something to play for at four games back in the NL East.
Rays (Cobb, 9-9) at Red Sox (Lester, 9-13), 7:10 p.m. Preview >
Winners of six straight, Tampa Bay has played itself right back into the AL Wild Card race. The Rays, trailing by three games, send Alex Cobb to the hill on Wednesday.
Brewers (Marcum, 5-4) at Reds (Arroyo, 12-8), 7:10 p.m. Preview >
The Reds are playing for the top seed in the National League, while Milwaukee is simply playing for its playoff life at 4 1/2 games back of St. Louis.
Cardinals (Carpenter, 0-0) at Astros (Norris, 5-13), 8:05 p.m. Preview >
St. Louis is slowly inching closer to the No. 2 Wild Card in the NL, and it sends Chris Carpenter to the hill on Wednesday, looking for his first win since Game 7 of the 2011 World Series.
A's (Parker, 11-8) at Rangers (Perez, 1-2), 8:05 p.m. Preview >
So far this week's pivotal AL West series in Texas hasn't disappointed, and Jarrod Parker and Martin Perez take the hill for an encore to Tuesday's 10-inning thriller.
Indians (Masterson, 11-15) at White Sox (Santiago, 3-1), 8:10 p.m. Preview >
The White Sox lead has slowly slipped away, but they're still tied with Detroit as they face Cleveland in a rubber match on Wednesday.
Mariners (Hernandez, 13-8) at Angels (Wilson, 12-10), 10:05 p.m. Preview >
The Angels, who are two games back in the AL Wild Card race, have the best record in the AL since Aug. 21, but they'll get a serious test in Seattle's Felix Hernandez on Wednesday.
D-backs (Miley, 16-10) at Giants (Cain, 15-5), 10:15 p.m. Preview >
San Francisco still has an outside shot at home-field advantage for the first round of the playoffs. The D-backs, meanwhile, are six back in the Wild Card with eight to play.
Wild Card: A's at Orioles
Division Series: Yankees vs. Tigers or White Sox | Rangers vs. Wild Card winner
Wild Card: Cardinals at Braves
Division Series: Reds vs. Giants | Nationals vs. Wild Card winner
For the 2012 postseason, the team with the better record will play the first two games on the road to start the Division Series.
Postseason Bracket »
To calculate a team's magic number, take the number of games it has remaining and add one. Then subtract the difference in the number of losses between that team and its closest pursuer.
A tiebreaker game will be played to determine a division winner, even if the tied clubs are assured of participating in the postseason. If a division championship tiebreaker is necessary, the head-to-head record between the clubs will determine home-field advantage. If the head-to-head record is tied, then division record will be the next tiebreaker.
If two clubs are tied for the two Wild Card berths, home-field advantage will be determined by the head-to-head record between the clubs. If the head-to-head record is tied, then division record will be the next tiebreaker.
Tiebreaker rules »
2012 postseason schedule
Wild Card playoff games: Oct. 5
Division Series: Oct. 6-12
AL Championship Series: Oct. 13-21
NL Championship Series: Oct. 14-22
World Series: Oct. 24-Nov. 1