3 Most Important Series for Diamondbacks As Playoff Race Heats Up

The Arizona Diamondbacks are staying alive in the playoff race. After earning a critical series win over the Cincinnati Reds on Sunday, they're staring down a hot playoff chase as the season continues to grow long.

At 69-62, and sitting two games back of the final Wild Card spot, Arizona is not in the most ideal position, but they are firmly in the mix of a crowded National League playoff picture.

The Diamondbacks ultimately can very well control their own destiny as 2026 winds down. But there will be some crucial series lying ahead. As August turns to September, games begin inching closer to must-win territory.

These are the three series that will carry the most playoff importance as the playoff chase gets hot:

Diamondbacks vs Phillies (August 31-September 2)

Aug 23, 2026; Philadelphia, Pennsylvania, USA; Philadelphia Phillies designated hitter Kyle Schwarber (12) celebrates his walk-off home run in the ninth inning against the St. Louis Cardinals at Citizens Bank Park. Mandatory Credit: Eric Hartline-Imagn Images TPX IMAGES OF THE DAY | IMAGN IMAGES via Reuters Connect

The Phillies have been exceptionally hot, but they're still within striking distance for the Diamondbacks. Philadelphia is 73-58 and facing the Seattle Mariners for a three-game series this week.

They're only four games ahead of Arizona and occupy the second Wild Card spot. The Diamondbacks currently hold a 2-1 season series lead over the Phillies, so this series will determine who owns the tiebreaker.

Considering Philadelphia has won nine in a row, it may not come down to a tiebreaker. But it also could mean a slump is coming. Taking care of business in this series will set Arizona up with a much-needed advantage over one of their direct competitors.

Diamondbacks vs Marlins (September 14-16)

Aug 23, 2026; Miami, Florida, USA; Miami Marlins shortstop Otto Lopez (6) congratulates Esteury Ruiz (3) following a win over the Washington Nationals at loanDepot Park. Mandatory Credit: Jim Rassol-Imagn Images | IMAGN IMAGES via Reuters Connect

The Diamondbacks were swept by the Marlins in Miami in their last three-game series matchup. Arizona would need to sweep this series to avoid losing the tiebreaker. That might not be an incredibly realistic outcome to expect.

But the Marlins are quietly creeping back into Wild Card contention. They are currently the closest threat behind the Diamondbacks in the standings at 67-64. They cannot be counted out.

Arizona likely won't be able to wrest a tiebreaker away from Miami in this series, but winning two out of three at minimum would be extremely helpful in holding their position in the playoff picture. Losing two could allow Miami to leap ahead of Arizona.

Diamondbacks vs Padres (September 25-27)

Aug 23, 2026; San Diego, California, USA; San Diego Padres right fielder Fernando Tatis Jr. (23) is congratulated by third baseman Manny Machado (13) after hitting a solo home run during the eighth inning against the Minnesota Twins at Petco Park. Mandatory Credit: Denis Poroy-Imagn Images | IMAGN IMAGES via Reuters Connect

For the third season in a row, the Diamondbacks' playoff hopes could very well come down to a three-game series with the San Diego Padres in the final week of the regular season.

The Padres are 71-60 and nearly as hot as the Phillies. They have won seven of their last 10 games. The Diamondbacks have split the season series with their division rivals, 5-5, so far this year, so this series will determine the tiebreaker — if that remains a factor by the end of September.

Should both teams be in contention by the final series of 2026, this one could mean everything.

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