(Would a complete collapse by the Braves or Red Sox be more shocking? Vote here.)

Michael Bourn and the Braves are falling fast. (Marc Serota/Getty Images)

That at the start of September, when neither team appeared capable of the full-fledged free-falls they’ve since experienced.

Following Sunday’s loss to the Washington Nationals, Atlanta is a dismal 9-15 in September. That same record would have given Boston the AL wild-card, but instead they’ve gone 7-18. Both enter their final series of the regular season with a one-game lead on the second place team and all the momentum working against them.

To understand the scope of just how bad things have gone for the Red Sox and Braves this month, here’s the key stat from Dave Sheinin’s Monday story:

A hundred-plus years of baseball history had proven one thing about pennant races: A nine-game lead in September is essentially unassailable. There have been epic collapses, colossal chokes and monumental meltdowns. But no team in history — not the infamous 1964 Philadelphia Phillies, not the 1978 Boston Red Sox, not the 1995 California Angels, not the 2007 New York Mets — has ever failed to make the postseason after holding a lead of nine or more games in September.”

The Red Sox led the AL race by nine games as recently as Sept. 3 and the Braves held an 8 1/2 game lead on Sept. 6.

Now both need to shake their recent funks immediately or they’ll miss out on a postseason that seemed like a near sure-bet a mere month ago.

For the Red Sox — who hold a one-game lead over AL East rivals Tampa Bay — the road takes them to Baltimore to face the division doormat but recently red-hot Orioles. They needed a 14th-inning home run from Jacoby Ellsbury to maintain their on-game coushion on the hard-charging Rays. Tampa hosts the Yankees, who knocked both teams down a peg over the last week, and can ultimately have a say in which division rival makes it to October.

The Braves, meantime, get NL East champions Philadelphia and their brutal starting staff at Turner Field where they’ll almost assuredly need to at least win two of three. The second-place St. Louis Cardinals close out in Houston against the worst team in baseball.

Here’s a look at the matchups and projected starters.

American League (Red Sox currently lead Rays by 1 game)

Red Sox at Orioles

Mon. — Becket vs. Hunter, 7:05

Tues. — Bedard vs. Britton, 7:05

Wed. — Lester vs. Simon, 7:05

Yankees at Rays

Mon. — Noesi vs. Shieldgs, 7:10

Tues. — Colon vs. Hellickson, 7:10

Wed. — ??? vs. Price, 7:10

National League (Braves currently lead Cardinals by 1 game)

Phillies at Braves

Mon. — Lee vs. Delgado, 7:10

Tues. — Oswalt vs. Lowe, 7:10

Wed. — Hamels vs. Hudson, 7:10

Cardinals at Astros

Mon. — Garcia vs. Rodriguez, 8:05

Tues. — Westbrook vs. Sosa, 8:05

Wed. — Carpenter vs. Myers, 8:05

If either or both teams complete the epic collapse, they’ll only be able to look in the mirror come Oct. 1 and know: you do it to yourself.