As baseball's postseason field stitched itself together a little bit more on the final Saturday of summer, a few teams have pulled close to sewing up their ticket to October, while a couple of the races remain completely unraveled.

As the Pulse of the Postseason ticks toward autumn's cooler days and even bigger games, the raucous American League Wild Card race and the stirring National League Central situation brought thrills on the boys' last day of summer, leaving plenty up in the fall air as the calendar's season of October dreams begins Sunday.

The autumnal equinox is always a sign things are getting down to it in baseball, and on Sunday there could be as many as four teams joining the postseason invitation list. So far, two -- AL East champ Boston and NL West champ L.A. -- of the 10 invites have been earned.

The Braves of the NL East and the A's of the AL West are both sitting on a magic number of one to win their respective divisions after Saturday's action, which means all they have to do is win Sunday.

"We know it's right there," A's right-hander Jarrod Parker said after a winning effort against Minnesota. "If we handle what we do and we win games, it's going to happen."

The Cardinals hold that preciously small magic number of one to clinch a postseason spot, and the Tigers are down to two for the same goal after a startling comeback Saturday night.

In a sense, Saturday was a day that brought more teams closer than any time before in this stretch run, yet it kept certain outcomes far from decided.

The day began with that race in Tampa Bay, where the Rays topped the Orioles in a game that began just hours after an 18-inning thriller on Friday night. Alex Cobb tossed 8 1/3 strong innings with 12 strikeouts in a 5-1 victory.

The win ensured the Rays would retain the top Wild Card spot at day's end, regardless of what the Indians and Rangers might do.

Also early on, a three-run rally by the Cubs in the eighth spoiled the Braves' attempt to wrap up their division, as Chicago took a 3-1 win that delayed Atlanta's celebration. The outcome meant the Braves would have to wait out the Nationals' home game against Miami, hoping for a Washington loss to clinch -- but the game in Washington never got off the ground, postponed by rain, setting up a day-night doubleheader Sunday.

So the Braves, dominant in the National League East from the outset, have to wait at least another day to claim their first division title since 2005.

After a delay of about two hours following a Bay Area rainstorm, Oakland made quick work of the Twins again, piling up a 9-1 win. Alberto Callaspo, acquired from the Angels in July, went 4-for-5 with a two-run homer, one of three on the day for the A's, who have hit 65 homers in their last 42 games.

The A's knew then that they'd be able to clinch the American League West after their rain-delayed afternoon home win over Minnesota -- but only if the Rangers couldn't hold on to their early lead in Kansas City. While the A's awaited the Rangers-Royals result, the Indians maintained the No. 2 Wild Card spot for another day with a 4-1 win over the Astros.

The Tribe's Michael Brantley provided the first-inning fireworks during the game with a two-run homer, and Nick Swisher literally provided them afterward, sponsoring a pyrotechnics show that wound up being a victory celebration.

The Rangers, meanwhile, avenged their loss in the opener Friday with a 3-1 win over the Royals that had a significant impact on two races. It kept Oakland's AL West celebration on hold for at least another day, and it helped create a two-tiered race in the AL Wild Card. It left the Rays, Indians and Rangers within a game of each other, with the Yankees -- 6-0 winners over San Francisco behind Ivan Nova -- three back and the Royals and Orioles both 3 1/2 back.

The show wasn't over elsewhere, especially in the NL Central, which has become a bit of a black-and-blue division as they beat up on each other down the stretch.

At PNC Park, the Pirates used a two-run homer from Russell Martin and a pair of runs in the sixth to take a two-run lead into the ninth, and this time it was Jason Grilli with the save in a 4-2 win over the Reds that put the Pirates back in second place in the division.

Said Grilli, the All-Star now returning to health who had his first save since July 21: "A big win for us, obviously, and it was a lot of fun to be out there. If you don't like that ... you don't like Christmas."

The Cardinals won their 11th in their last 15, charging to a 7-2 win at Milwaukee. Matt Carpenter passed Stan Musial with his 54th double, Matt Adams went deep again, and St. Louis retained a two-game cushion in the NL Central over the Pirates, with the Reds three back and leading the Nationals by 4 1/2 games for the No. 2 Wild Card slot.

As the night wore on, it became apparent the Nationals would not get their game in under the stormy D.C. skies. Although they were ready for anything, they'll have to wait for Sunday.

The one extra-inning game of the night sure didn't seem like it would become one, but the Tigers erased a six-run deficit in the ninth inning against the White Sox and wound up winning a 7-6 stunner in 12 innings, lowering their magic number to two in the division, and for a postseason spot.

The two teams that are in the postseason party already got their games in, too, the Red Sox falling to the Blue Jays and the Dodgers beating the Padres.

***

There are clinching scenarios all over the map for teams hoping to make their reservations for October when baseball's postseason races wake up to the first day of fall on Sunday.

One game early in the day will be key to a couple of those scenarios -- the one not played Saturday, now Game 1 of the Marlins-Nationals day-night doubleheader. A Nationals loss in that one would punch the ticket to October for both the Braves and Cardinals, regardless of what those teams do.

The Nationals, winners of 12 of their last 15, will send Dan Haren to the mound in what would have been his normal time slot anyway hoping to stave off elimination for another day, knowing they'll be needing a lot of help in the last week.

"So, that means we have to win out and hope somebody slips," Nationals manager Davey Johnson said.

Of course, the Braves would just as soon take care of business themselves in their finale at Wrigley Field. Ditto the Cardinals when they meet the Brewers, looking for a hard-fought sweep at Miller Park in the Sunday night game.

The A's also can punch their ticket merely by winning one more game against the Twins -- they've outscored Minnesota in the first three games of the four-game set, 28-7.

Meanwhile, the Tigers can clinch either the AL Central or a postseason spot, but they would need to win and either Cleveland or Texas to lose to nail it down.

The AL Wild Card race, now a six-team race with two tiers, in the standing will be contested in a couple of head-to-head matchups: Orioles-Rays and Rangers-Royals. The Indians -- winners of seven straight against sub.-500 teams and a Majors-best 49-18 against those clubs on the year -- will host the Astros for the finale of a four-game set.

And no matter how the Yankees' game turns out, it will be a special day at the Stadium against the Giants with Mariano Rivera Day, the bonus of Andy Pettitte's final home start before also retiring following 2013.

The Yankees join the Orioles and Royals at three or more out of the race, with the Rays a half-game ahead of the Indians, who are a half-game ahead of the Rangers.

NL Central/NL Wild Card drama will continue to unfold at PNC Park with the finale between the Reds and Pirates -- with a season-ending series in Cincinnati slated for the following weekend. The Bucs can clinch a long-awaited playoff spot with a win and two Nationals losses.

Meanwhile, the Red Sox host the Blue Jays in their home finale with a 1 1/2-game lead over the A's for the American League's best record, and the Dodgers meet the Padres aiming for win No. 90.

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

Astros (Bedard, 4-11) at Indians (Kluber, 9-5), 1:05 p.m. Preview >

Giants (Petit, 4-0) at Yankees (Pettitte, 10-10), 1:05 p.m. Preview >

White Sox (Johnson, 1-2) at Tigers (Sanchez, 14-7), 1:08 p.m. Preview >

Reds (Arroyo, 13-11) at Pirates (Locke, 10-6), 1:35 p.m. Preview >

Marlins (Koehler, 3-10) at Nationals (Haren, 9-13), Game 1, 1:35 p.m. Preview >

Blue Jays (Dickey, 13-12) at Red Sox (Doubront, 10-6), 1:35 p.m. Preview >

Orioles (Feldman, 12-10) at Rays (Romero, 0-0), 1:40 p.m. Preview >

Rangers (Ogando, 7-4) at Royals (Shields, 12-9), 2:10 p.m. Preview >

Braves (Teheran, 12-8) at Cubs (Jackson, 8-16), 2:20 p.m. Preview >

Twins (De Vries, 0-0) at A's (Gray, 3-3), 4:05 p.m. Preview >

Dodgers (Greinke, 15-3) at Padres (Cashner, 10-8), 4:10 p.m. Preview >

Marlins (Flynn, 0-2) at Nationals (Strasburg, 7-9), Game 2, 7:05 p.m. Preview >

Cardinals (Kelly, 9-4) at Brewers (Peralta, 10-15), 8:05 p.m. Preview >

If the postseason started today ...

AMERICAN LEAGUE

Wild Card: Indians at Rays
Division Series: Wild Card at Red Sox* | Tigers at A's

NATIONAL LEAGUE

Wild Card: Reds at Pirates
Division Series: Wild Card at Braves | Dodgers* at Cardinals

* - clinched postseason spot

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 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 »

2013 postseason schedule

NL Wild Card Game: Oct. 1
AL Wild Card Game: Oct. 2
NL Division Series begin: Oct. 3
AL Division Series begin: Oct. 4
NL Championship Series begins: Oct. 11
AL Championship Series begins: Oct. 12
World Series begins: Oct. 23