WASHINGTON -- The Nationals keep saying their goal is to win the National League East, but they are struggling to do so right now as they lost to the Brewers, 6-2, at Nationals Park on Sunday afternoon.

The Nationals are now 92-60 and 4 1/2 games ahead of the Braves in the NL East standings. Atlanta edged the Phillies, 2-1, on Sunday. The Nats' magic number to win the division remains at six.

Washington, with Jordan Zimmermann on the mound Monday, hopes to split the four-game series at home. The Nationals then hit the road as they work toward clinching. They'll first be in Philadelphia for three games before heading to St. Louis for three.

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

Brewers (Estrada, 4-6) at Nationals (Zimmermann, 11-8), 1:05 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