PHOENIX -- The Giants trust in their success, but they refuse to get carried away with it.

"I don't think anybody's taking anything for granted," catcher Buster Posey said.

The National League West front-runners extended their winning streak to four games with Saturday's 3-2 victory over the Arizona Diamondbacks. But second-place Los Angeles also won, freezing the Giants' division lead at 7 1/2 games.

Nevertheless, the Giants have an excellent chance to clinch the division at home. Following Sunday's series finale against the D-backs here, San Francisco will play its next 10 games at AT&T Park.

Today's key games to watch (all times ET)
Giants (Vogelsong, 12-8) at D-backs (Corbin, 5-7), 4:10 p.m. Preview >

Cardinals (Wainwright, 13-13) at Dodgers (Fife, 0-1), 4:10 p.m. Preview >

Reds (Latos, 12-4) at Marlins (Nolasco, 12-12), 1:10 p.m. Preview>

If the postseason started today ...

AMERICAN LEAGUE
Wild Card: Second Wild Card at First Wild Card
Division Series: Second-best AL record vs. Third-best AL record | Best AL record at Wild Card winner

NATIONAL LEAGUE
Wild Card: Second Wild Card at First Wild Card
Division Series: Second-best NL record vs. Third-best NL record | Best NL record at 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 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