3 Series in September That Will Determine the Phillies Season

The Philadelphia Phillies will have these three series circled on the calendar down the stretch.

Aug 30, 2026; Anaheim, California, USA; Philadelphia Phillies left fielder Brandon Marsh (16), right, is greeted by second baseman Bryson Stott (5) after defeating the Los Angeles Angels at Angel Stadium. Mandatory Credit: William Liang-Imagn Images | IMAGN IMAGES via Reuters Connect

The Philadelphia Phillies were one of the best teams in baseball in August, erasing what had been a painfully slow start for the team out of the gate in the second half.

With a 20-7 record entering the final day of the month, the Phillies have solidified their standing in the National League playoff picture. Currently the No. 2 Wild Card in the NL, Philadelphia has the Atlanta Braves back in their sights for the NL East race as well.

Will they be able to chase their rivals down? If they are going to do that, they are going to have to continue playing at a high level and overcome some challenges with their schedule.

Here are the three series that will determine how the Phillies season will go.

3. Vs. Milwaukee Brewers Sept. 22-24

Jun 13, 2026; Milwaukee, Wisconsin, USA; Philadelphia Phillies right fielder Brandon Marsh (16) hits a single to drive in a run in the eighth inning against the Milwaukee Brewers at American Family Field. Mandatory Credit: Benny Sieu-Imagn Images | IMAGN IMAGES via Reuters Connect

This starts a brutal stretch to the end of the regular season for Philadelphia. The Milwaukee Brewers currently have the best record in baseball and will host them for three games at Citizens Bank Park before hosting the Tampa Bay Rays, who currently have the best record in the American League.

These are great measuring-stick opportunities for the Phillies to see how they stack up with two of the best teams in the MLB. Getting a look at two teams you may run into during the postseason in the final week of the regular season can be used to Philadelphia’s advantage as well.

2. @ Arizona Diamondbacks Aug. 31-Sept. 2

Apr 12, 2026; Philadelphia, Pennsylvania, USA; Philadelphia Phillies infielder Bryce Harper (3) is caught stretching a single by Arizona Diamondbacks infielder Geraldo Perdomo (2) in the fourth inning at Citizens Bank Park. Mandatory Credit: Kyle Ross-Imagn Images | IMAGN IMAGES via Reuters Connect

The Phillies are completing their nine-game West Coast trip with a visit to Chase Field to play the Arizona Diamondbacks. This will have a major impact on the NL Wild Card picture because the Diamondbacks are one of the teams that are chasing Philadelphia, along with the San Diego Padres; the only other team over .500 right now in the race is the Miami Marlins.

This is an opportunity for the Phillies to bury Arizona in the race, building upon the 4.5-game lead they have entering the series. After losing two out of three to the Diamondbacks in their first series in April, Philadelphia will be motivated to even the season series at the very least.

If the Phillies lose this series, they will lose the tiebreaker, which would further complicate things for them down the stretch. A 2-1 series victory or sweep would give them a truly commanding lead.

1. Seven Games vs. Atlanta Braves

Apr 26, 2026; Cumberland, Georgia, USA; Philadelphia Phillies center fielder Brandon Marsh (16) and Atlanta Braves catcher Drake Baldwin (30) check on home plate umpire Mike Muchlinski (76) after he was hit by a foul ball during the ninth inning at Truist Park. Mandatory Credit: Dale Zanine-Imagn Images | IMAGN IMAGES via Reuters Connect

If Philadelphia is going to chase down the Braves in the NL East race, there is no better way than to beat them head-to-head. A massive four-game series starts on Sept. 4 and runs through Sept. 7 at Citizens Bank Park.

After that, the teams face off again, this time at Truist Park in Atlanta, on Sept. 11-13. To have a realistic shot at taking the NL East crown, the Phillies likely have to go 5-2 at a minimum against their rivals.

Entering play on Aug. 31, Philadelphia is five games behind in the standings.