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09/20/12 10:18 PM ET

Reds' Path to the Postseason: Sept. 21, 2012

CHICAGO -- The Reds became the first team in baseball to clinch a Wild Card playoff berth on Thursday with a 5-3 win over the Cubs. They also lowered their magic number to clinch the National League Central to two after the Cardinals swept the Astros.

At 91-59, the Reds can clinch their division with a win over the Dodgers on Friday, combined with a Cardinals loss to the Cubs. Meanwhile, the Reds are neck and neck with the Nationals (91-58) for the best record in baseball, only a half-game back.

Cincinnati has 12 games remaining, all against teams that are still alive for a Wild Card spot.

"There's a lot of work left," reliever Sean Marshall said. "We've still got two weeks left in the season. Of course, we want to finish strong and get hot at the end. We've got a lot of games to win if we want to win the World Series. It's not an easy road, but the road to get here wasn't easy either. We're up to it and can have different guys step up. We're sitting in a pretty good spot."

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

Cardinals (Carpenter, 0-0) at Cubs (Volstad, 3-10), 2:20 p.m. Preview >

Brewers (Marcum, 5-4) at Nationals (Jackson, 9-10), 7:05 p.m. Preview >

If the postseason started today ...

This is how the teams would match up: 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 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 the 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 the 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

Mark Sheldon is a reporter for MLB.com. Read his blog, Mark My Word, and follow him on Twitter @m_sheldon. This story was not subject to the approval of Major League Baseball or its clubs.