In the first year of its existence, the second National League Wild Card berth has become the subject of a furious pursuit.

While the Braves maintain a strong grip on the top NL Wild Card position, six clubs now sit within four games of the other spot, thanks to another day of compression in the standings.

The top three teams in the race all continued to slide backward on Wednesday, as the Cardinals were swept in San Diego, the Dodgers in Arizona and the Pirates in Cincinnati. St. Louis maintains a 2 1/2-game edge on Pittsburgh and a one-game advantage over Los Angeles heading into its four-game series beginning on Thursday at Dodger Stadium.

Wells Fargo

"We're right there," Cardinals catcher Yadier Molina said after his club's ninth-inning rally fell short. "It's going to take one pitch, one swing, one hit to get back on track, and hopefully it's [Thursday]."

Those top three now have plenty of company, as recent surges by the Phillies (three games out) and Brewers (three games) have turned the final few weeks of the regular season into a free-for-all, with the D-backs also sitting only four games behind. The Phils have been particularly hot, beating the Marlins on Wednesday for their seventh straight win, with help from Jimmy Rollins' key two-run homer.

"We're in it," Phillies manager Charlie Manuel said. "I'd say we're dead in it, yeah."

Other races feature plenty of drama of their own. The Orioles and Yankees both won on Wednesday to remain tied atop the American League East, while the Tigers pulled within a game of the White Sox in the Central.

The A's, on the other hand, won their third straight against the Angels and sixth overall to remain in front of the AL Wild Card chase. The Angels sit 3 1/2 out of the second spot and a half-game back of the Rays.

The Giants, Nationals and Reds all won to increase their already solid division leads in the NL, while the Rangers' victory over the Indians allowed Texas to stay three games up on Oakland in the AL West.

Today's key games to watch (all times ET)

Rays (Hellickson, 8-10) at Orioles (Chen, 12-9), 12:35 p.m. Preview>
The Rays need Jeremy Hellickson to act as stopper when they try to avoid a crushing sweep at Camden Yards, where the Orioles pulled off a dramatic walk-off win on Wednesday.

A's (Anderson, 4-0) at Angels (Weaver, 16-4), 3:35 p.m. Preview>
Jered Weaver, recovered from elbow tendinitis, makes his first start since Sept. 2, while Brett Anderson goes for his fifth straight win since coming off the disabled list and Oakland's seventh in a row.

Yankees (Hughes, 14-12) at Red Sox (Doubront, 10-8), 7:10 p.m. Preview>
The Yankees are looking for back-to-back victories for the first time since Aug. 15, while Phil Hughes hasn't won consecutive starts since two weeks earlier.

Indians (McAllister, 5-7) at Rangers (Holland, 10-6), 8:05 p.m. Preview>
The Rangers, who sit atop the AL West, need a win on Thursday to collect their first series sweep since taking three from the Padres in mid-June.

Phillies (Cloyd, 1-1) at Astros (Abad, 0-4), 8:05 p.m. Preview>
The surging Phils have won seven straight to jump back into the Wild Card race, but have rookie Tyler Cloyd pitching on short rest for the first time in his career.

Tigers (Verlander, 13-8) at White Sox (Sale, 16-6), 8:10 p.m. Preview>
Two of the top pitchers in the AL will go head-to-head, with Justin Verlander trying to pull his Tigers even with Chris Sale's White Sox atop the AL Central.

Cardinals (Lynn, 14-7) at Dodgers (Beckett, 6-13), 10:10 p.m. Preview>
The Dodgers missed a chance to tie the Cardinals for the second National League Wild Card spot on Wednesday, but have another chance on Thursday, with St. Louis starting a series at Chavez Ravine.

If the postseason started today ...

AMERICAN LEAGUE
Wild Card: Orioles or Yankees at A's
Division Series: Orioles or Yankees vs. White Sox | Rangers vs. Wild Card winner

NATIONAL LEAGUE
Wild Card: Cardinals at Braves
Division Series: Reds vs. Giants | Nationals vs. Wild Card winner

Postseason Bracket »

Postseason 101

Magic numbers
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.

Tiebreaker scenarios
A tiebreaker games 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