We’ve already stepped into September, which indicates that the concluding month of the 2025 Major League Baseball season has begun. This signifies four weeks of defining baseball in relation to awarding MLB’s six division titles, 12 playoff spots, home-field advantages, and first-round byes. The stakes are as elevated as the unbearable heat of July.
As we advance toward playoff baseball, let’s cherish the month ahead by spotlighting the numerous matchups that will shape what October has in store. Below, you’ll find precisely that — the confrontations during September that represent the initial vital moves toward crowning a World Series champion for 2025. Let’s proceed in a tense and rule-breaking sequential manner …
The initial pair of games in this three-game series are already complete, yet we’ll include it here nonetheless because the series finale is still scheduled. The Tigers are nearly certain to clinch the AL Central for the first time since 2014, while the Mets are striving to stay in third and the last wild card position in the NL (and possibly apply some late pressure on the first-place Phillies). Thus, consider this one a Theoretical World Series Preview.
Sept. 1, 3-4: Philadelphia Phillies at Milwaukee Brewers
We transition from that to a Theoretical NLCS Preview, which features the seldom-seen Tuesday off day. Both of these NL powerhouses maintain a relatively secure lead in their divisions, and the Brewers have a firm hold on a first-round bye (the two division winners with the best records in each league receive a bye to the LDS). Meanwhile, the Phillies find themselves in a close contest with the Dodgers (and by extension the Padres, should they surpass L.A. at some juncture) for that sought-after second bye on the NL side. In this regard, this matchup is more significant for Philly.
Now we present a Theoretical ALCS Preview that is already in progress. This marks the last time the author will mention the presence of a Theoretical Playoff Series Preview. It’s also one of the most riveting rivalries in the junior circuit, at least in recent times. The Astros are attempting to ward off the Mariners and the Rangers in the AL West. Meanwhile, the Yankees are in wild card territory and still intent on overtaking the Blue Jays in the AL East.
The Mets currently hold the third and final wild card position in the NL, with the Reds closest in the race for that last playoff spot. The Queenslanders enjoy a significant lead given the relatively late stage, meaning the Reds urgently need to seize this series to reduce the Mets’ advantage. If the Reds manage to win two of three or achieve a sweep, they’ll also capture the tiebreaker over the Mets. Both Cincy and the Mets face some of the toughest remaining schedules in all of MLB.
Sept. 5-7: Texas Rangers at Houston Astros
The Rangers have been performing closer to expectations recently, thereby returning to the conversation in the AL wild card race and potentially the AL West. Notably, at the time of writing, only the Yankees and Red Sox possess a better run differential than Texas. This series marks their first of two chances to directly impact Houston’s lead in the division. Seattle will be keeping tabs for multiple reasons.
Sept. 5-7: Toronto Blue Jays at New York Yankees
As mentioned earlier, the Yankees (and Red Sox) are still very much in the AL East contest, which makes this matchup between the Yankees and the leading Jays critical. Toronto holds the tiebreaker over both the Yankees and Boston, so if the AL East results in any kind of tie involving the Jays, they will claim the division title. This circumstance heightens the urgency for the Yankees.
Sept. 8-11: New York Mets at Philadelphia Phillies
While there’s still time for changes, at this moment the Mets will need to grab at least three of four in this series to maintain their division hopes. This is, of course, assuming that the Phillies don’t falter before or after this series.
Sept. 9-11: Detroit Tigers at New York Yankees
As previously stated, the Tigers are vying for a bye and the top seed in the AL. The Yankees are determined to chase down the Jays in the AL East and position themselves ahead of the archrival Red Sox in the AL standings.
Sept. 9-11: Houston Astros at Toronto Blue Jays
Beyond the pressing goal of preserving their respective division leads, these two teams might also end up competing for one of the two available byes for AL teams. Houston swept their initial series against each other this season, meaning one more victory will secure them the tiebreaker over the Jays.
Sept. 12-14: Kansas City Royals at Philadelphia Phillies
A strong July and August have revitalized KC’s chances in the AL wild card race, making this a series of significance. It holds more weight for the Royals, who are aiming to catch the Mariners for that third wild card position, but the Phillies, again, are locked in a tight contest for a bye on the NL side.
Sept. 12-14: New York Yankees at Boston Red Sox
This storied rivalry comes with playoff consequences for the first time in quite a while. Both teams are still contending in the AL East and occupy the top two wild card spots in the AL. This series could play a key role in determining who hosts that potential Wild Card Series clash.
Sept. 12-14: Texas Rangers at New York Mets
Wild card stakes exist for both sides, with a sprinkle of division-race intrigue as well? Absolutely. That’s the situation for this series. Will Jacob deGrom face his former team for the first time in his career?
Sept. 15-17: Philadelphia Phillies at Los Angeles Dodgers
As noted, we will refrain from indicating that this is a Theoretical NLCS Preview. Again, it seems likely to be a competitive race between the Phillies and the eventual NL West champion for that second bye in the NL. That’s the probable angle for Philly here, while the Dodgers will keep an eye on the second-place Padres.
Sept. 15-17: Texas Rangers at Houston Astros
This represents the second and final Rangers-Astros matchup of September and, should trends continue, it will be relevant to both the AL West and AL wild card races.
Sept. 16-18: Seattle Mariners at Kansas City Royals
This could help determine the last playoff spot in the AL. The M’s currently lead, but KC has the opportunity to chip away at that lead during this home series. The season series between these clubs is tied at 2-2, making this matchup pivotal for the tiebreaker.
Sept. 16-18: San Diego Padres at New York Mets
The Padres are working to catch the Dodgers in the NL West, but they have no more direct encounters left with L.A. and fall short in the tiebreaker. San Diego is currently in the second wild card position in the NL, with a chance to secure the top spot and thus host a Wild Card Series. You’re aware of the Mets’ current situation and goals. Notably, the Padres are under .500 on the road this season, while the Mets have been among MLB’s best at home.
Sept. 19-21: Seattle Mariners at Houston Astros
The scenario is clear now. The Astros maintain a slim lead over the Mariners in the AL West, and this marks their final direct encounter of the regular season. The season series is also deadlocked at 5-5 heading into this contest, meaning the tiebreaker will be determined by whichever team claims two of three or manages a sweep.
Sept. 19-21: Toronto Blue Jays at Kansas City Royals
Toronto is aiming for its first division title since 2015 while the Royals are attempting to reach the playoffs for a second consecutive year.
Sept. 22-24: Milwaukee Brewers at San Diego Padres
The Padres face one of the easier remaining schedules in all of MLB, but this series is a notable exception. Of course, this assumes that the Brewers haven’t secured the NL Central and a bye by this time and are instead in «rest and reset for the playoffs» mode.
Sept. 23-25: New York Mets at Chicago Cubs
The Cubs are positioned at the top wild card slot while still hoping to achieve a minor miracle against the Brewers in the NL Central. A more pragmatic goal for the North Siders would likely be to stay in top wild card position and thus earn the chance to host the Wild Card Series. By this stage, we’ll probably know whether the Mets have any realistic chance of catching the Phillies or whether their focus will have shifted to wild card scenarios.
Sept. 23-25: Boston Red Sox at Toronto Blue Jays
The Red Sox have been one of MLB’s most formidable teams since the calendar turned to July, so it won’t be surprising if the AL East hinges on this series (the Yankees undoubtedly may have input on that).
Sept. 26-28: Detroit Tigers at Boston Red Sox
We’ll reiterate those AL East implications previously mentioned, and by this time the Tigers may be striving to secure a first-round bye.
Sept. 26-28: Los Angeles Dodgers at Seattle Mariners
Could this concluding series of the regular season arrive with both West divisions still at stake? That’s a distinct possibility given the current margins. The Dodgers hold a lead over the Padres at present, while the M’s are attempting to catch the Astros while remaining in wild card contention. Will this serve as Cal Raleigh’s last attempt for 60 homers?
