When Tuesday begins, expect the wild-card chase in the National League to become a free-for-all.

Heading into the final six games of the season, the Chicago Cubs and San Diego Padres are tied at 87-69 and sit one game ahead of the Philadelphia Phillies in the NL wild-card standings. They are the likely three teams that will get into the postseason via the wild card, but the Arizona Diamondbacks (82-74) are still alive at 4.0 games back.

Here's how the final six games look for each of the four teams:

Chicago Cubs: home vs. Miami for three, at Boston for three

San Diego: at Los Angeles Dodgers for three, home vs. Arizona for three

Philadelphia: home vs. Milwaukee for three, home vs. Tampa Bay for three

Arizona: at Colorado for three, at San Diego for three.

What are the NL wild-card tiebreakers to know?

If a tie were to occur with any or all of the three teams, the Cubs have the upper hand, going 5-1 against San Diego this year and 6-1 against the Phillies.

The Phillies, meanwhile, went 6-0 against San Diego this season.

Simply put, the Padres have the worst tie-breaker numbers if it comes down to any kind of tie for seeding purposes.

Should the Diamondbacks creep back into the mix, here are the key numbers to know: Arizona went 2-4 against Chicago this season and has split the season series with Philadelphia (3-3) and San Diego (5-5) so far.

The "so far" is the key as Arizona and San Diego will square off in the last three games of their respective seasons. Plenty could be on the line at Petco Park when those two meet this weekend.

Which NL wild-card team has the schedule advantage?

That would seemingly be the Phillies, who are the only one of the four teams to be at home for the rest of the regular season. However, Philadelphia ends the year with the current top seed in the NL (Milwaukee) and in the American League as well (Tampa Bay). Both of those top seeds still have things to play for as home field throughout the World Series could be decided this week between the Brewers and Rays.

The Cubs will get Miami inside the Friendly Confines and then travel to Boston to face the Red Sox, a team that will likely be locked into its postseason seeding by the time the Cubs arrive. However, there is also the potential for a major storm to hit New England this weekend, bringing wet weather to Fenway Park and potentially throwing the schedule completely off.

San Diego, meanwhile, could have the toughest road ahead, facing their old nemesis in the Dodgers in a series Los Angeles needs to win in order to keep pace for the top seed in the NL postseason. If Arizona doesn't stumble at Coors Field and any of the three teams above them falter, the Diamondbacks could come to San Diego with plenty of motivation.

Over the last six games, there could be plenty of scoreboard (and weather map) watching as wild-card seeding begins shaking out on Tuesday night.