Entering play on Tuesday, the National League East had four teams within nine games of the division lead: the Atlanta Braves, Philadelphia Phillies (three back), New York Mets (8.5), and Washington Nationals (nine). Calling the NL East a four-team race is a stretch -- though SportsLine does give three of the four postseason odds exceeding 20 percent -- but writing that this could be a season-defining week for the division is not. With the trade deadline inching closer and closer, it's possible that the NL East is a true two-team race come Monday.

That may seem like a bit much -- it's baseball; progress is measured in months, not days -- but consider the schedules (and the implications of those schedules) for each of the four teams.

We'll start at the back of the line, with the Nationals. Washington will play seven home games before Monday, including a day-night doubleheader on Wednesday to atone for a Monday rainout. All of those games will be against either the Phillies or the Braves. The Nationals will be the underdogs in both series, but an extreme result -- say, a 6-1 or 1-6 stretch -- would help them gain clarity as to whether it's too late in the season to make a real run at the playoffs.

The Mets aren't quite in the same predicament as the Nationals, but they're close. New York will try to avenge Monday's blowout loss against the Braves over the rest of the three-game series. From there, the Mets will jet off for a four-gamer against the Chicago Cubs. As with the Nationals, an extreme result -- and the Mets will be clear underdogs as well -- could leave the Mets either still in the race, or so far back as to justify considering a sell-off at the deadline.

Comparatively, the top two teams in the division don't have as much at stake this week. Even with losing efforts, the Braves and the Phillies will remain in the mix. That stated, obviously the Phillies would like to close the gap between them and the Braves for the division lead. Philadelphia's best chance at doing that will come over the weekend, when they play the lowly Miami Marlins three times. The Phillies should win (if not outright sweep) that series, suggesting they could be positioned to gain a game or two on the Braves, depending on how things go.

As for the Braves, by now you know their schedule: two more against the Mets, then three with the Nationals. If Atlanta missteps -- and hey, they haven't done so often as of late -- then the NL East will be a more interesting place. Another dominant week, however, and the Braves will have done their part to cement the division as a two-horse race -- one they'll continue to lead.