It's September, the pennant races in Major League Baseball are percolating, and the Red Sox and Yankees keep making news.

Funny how that works, isn't it?

The Pulse of the Postseason kept humming along on Tuesday night, and the two most storied franchises of the American League East were doing their part to keep themselves relevant all the way into October.

The Red Sox, of course, deserve top billing because they've earned it. Boston won yet again Tuesday, beating the Tampa Bay Rays, 2-0, to move to 30 games above the .500 mark (88-58), which is the best record in the AL and a mere percentage point behind Atlanta (87-57) for the top mark in the Majors.

"We've played good in a lot of aspects of the game," outfielder Jonny Gomes said. "With that being said, that's what we have to do to stay in first in Major League Baseball. You need to pitch, you need to play 'D' and you need to touch the dish. It's something we've done."

Clay Buchholz returned from a long stint on the disabled list to deliver five scoreless innings and improve to 10-0 this year. Mike Napoli kept on hitting. Koji Uehara has been unhittable. Add it up and it's seriously good vibes in Beantown at the right time of the year. Boston has a division lead of 8 1/2 games over the Rays with 16 games to go. The magic number for the Red Sox to clinch the division is 10.

The Red Sox are doing so well, even noted Rays fan Dick Vitale is noticing.

Meanwhile, the Yankees are not giving up and continued to battle away in the Wild Card standings. On Tuesday, they came back to beat the Orioles, 7-5, in a huge game.

Alfonso Soriano homered twice, continuing to prove how valuable he has been in pinstripes this time around, and the Yankees won despite Orioles slugger Chris Davis' Major League-leading 49th homer of the year. When it was over, the Yankees had gained a game on Baltimore and made the AL Wild Card standings even more confusing.

The National League Central remains a true September adventure. On Tuesday, the only club to lose ground in the three-team chase was the Reds, who were defeated by the Cubs, 9-1, and trail the division-leading Cardinals by three games.

The Pirates are a game back because they won in Texas while the Cardinals beat the Brewers.

And a similar scenario unfolded in the AL West, where the Oakland A's and Rangers lost, so Oakland kept its two-game advantage.

The Dodgers, Tigers and Braves remain in first place by large margins, and the Tigers' 9-1 win over the White Sox in Chicago, in which starter Rick Porcello went the distance for the first time in the big leagues, might have given Detroit some momentum after a shaky last month.

While the D-backs' days in the NL Wild Card race might be numbered, though, the Washington Nationals refuse to give up. They won again on Tuesday, beating the Mets, 6-3, for their fourth consecutive victory, as starter Jordan Zimmermann won his NL-leading 17th game. And while the odds still might be stacked against them for a playoff berth, they're only six games out of it.

"If we win out, I like our chances," Nationals manager Davey Johnson said. "The pitching has got to be better. The bullpen, at times, has been real shaky, but I like where we are at. I think we are five games in the loss column. … That's the biggest key going down the stretch."

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

Royals (Shields, 10-9) at Indians (Kazmir, 8-7), 12:05 p.m. Preview >
Kazmir is a leading Comeback Player of the Year contender, and he has the home crowd on his side against the always-tough, always-clutch Shields.

Cubs (Samardzija, 8-11) at Reds (Leake, 12-6), 12:35 p.m. Preview >
The Reds need to get out of this week's funk. Leake has been solid for them all year.

Pirates (Burnett, 7-10) at Rangers (Garza, 9-4), 2:05 p.m. Preview >
Trade Deadline pickup Garza gets the ball in a big spot for his new team as the Rangers try to make up ground on the division-leading A's.

Yankees (Pettitte, 10-9) at Orioles (Feldman, 12-10), 7:05 p.m. Preview >
Could this be one of the last starts in the great career of Andy Pettitte? Feldman and the Orioles hope so.

Braves (Minor, 13-6) at Marlins (Fernandez, 11-6), 7:10 p.m. Preview >
Minor's assignment is a major pain with NL Rookie of the Year favorite Fernandez on a recent roll. Atlanta's lefty hasn't been bad either.

Red Sox (Dempster, 8-9) at Rays (Cobb, 8-3), 7:10 p.m. Preview >
Cobb's comeback from his mid-season scare is a great story. The Rays need the right-hander more than ever to solidify their Wild Card standing.

Nationals (Haren, 8-13) at Mets (Wheeler, 7-4), 7:10 p.m. Preview >
Haren has been better of late and will need to be to keep the Nationals' postseason hopes afloat.

Tigers (Sanchez, 13-7) at White Sox (Quintana, 7-6), 8:10 p.m. Preview >
The Tigers have been scuffling over the last month and would like to see Sanchez reassert the dominance they've seen from him at points throughout the year, particularly against a struggling White Sox team.

Athletics (Gray, 2-3) at Twins (Pelfrey, 5-11), 8:10 p.m. Preview >
The A's young arms are deep and talented, and a good start from Gray could have Oakland considering using him in its postseason bullpen … or rotation.

Brewers (Estrada, 6-4) at Cardinals (Lynn, 13-10), 8:15 p.m. Preview >
The Cardinals are back in front in the crowded NL Central and would like to stay there. That means they can't afford to lose to a sub-.500 team at home.

D-backs (Corbin, 13-6) at Dodgers (Ryu, 13-5), 10:10 p.m. Preview >
This might be the day's best pitching matchup, with both starters going for win No. 14. The D-backs are desperate now and need a big one from Corbin.

If the postseason started today ...

AMERICAN LEAGUE
Wild Card: Rays at Rangers
Division Series: Wild Card at Red Sox | Tigers at A's

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

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