Former National Nyjer Morgan, the Brewers’ impish and polarizing center fielder, may be at the center of a series that includes two teams with very different styles. (Morry Gash/Associated Press)

It was Sept. 7, and as the St. Louis Cardinals and Milwaukee Brewers prepared to meet for the 18th and final time in the 2011 regular season, it seemed clear the relative fortunes of the bitter rivals were going in opposite directions. With a 9½-game lead in the NL Central division, the young, exuberant Brewers were beginning to think about such things as playoff rosters and rotations.

The older, more buttoned-down Cardinals, meantime, were playing some of their best baseball of the season, but they still trailed the Atlanta Braves by 7½ games in the wild card, and even the most optimistic among them suspected their September rally may have simply been too late to save them.

That night in St. Louis, Nyjer Morgan, the Brewers’ impish and polarizing center fielder, tossed a wad of tobacco in the general vicinity of Cardinals pitcher Chris Carpenter, touching off a minor brawl. On Twitter that same night, Morgan delivered what he figured were the ultimate last words:

“I hope those crying birds injoy watching tha Crew in tha Playoffs!!!” Morgan wrote. “Aaaaahhhhh!!!”

It is now a little more than a month later, and lo and behold the Brewers and Cardinals are not finished with each other for 2011. While the Brewers were coasting home to the division title, the Cardinals made a furious run to catch and pass the Braves and earn the wild card on the season’s final day. After a pair of riveting wins in their respective Game 5s on Friday, the teams are preparing for at least four, and as many as seven more games in the NL Championship Series, beginning Sunday at Milwaukee’s Miller Park.

Nyjer Morgan has energized the Milwaukee clubhouse with his personality, flair and multiple alter-egos. (DARREN HAUCK/Reuters)

“I am surprised [the Cardinals are here], just because of how far back they were,” Brewers Manager Ron Roenicke acknowledged. “But they’re really good. When they were playing at .500 ball, I did not think that was the team they were.”

All that regular-season familiarity not only bred contempt between the teams — it crystallized the vast differences in their personalities and temperaments. It is perhaps a generalization, but nonetheless true: The Cardinals see the Brewers as loud-mouthed, disrespectful punks, and the Brewers see the Cardinals as pompous, colorless squares with an inflated sense of entitlement. And neither side does much to hide the fact they don’t like the other.

“I think there are some differences in philosophy as to how the game should be played,” said Brewers left fielder Ryan Braun, “and that’s led to some problems.”

Even when one team was trying to strike a conciliatory tone, you could read between the lines and glimpse the truth. Cardinals right fielder Lance Berkman was trying to praise the Brewers for forging their own identity: “These guys have come up young together and have been great in their own way and established a different sort of tone as they’ve gone along,” he said.

But then Berkman added: “The two most important things in baseball are to have respect for the game and respect for your opponent. And anything that detracts from those two foundation rules is unacceptable, and [transgressions] have a way of working themselves out in the course of the game.”

Not surprisingly, the player who sits at the center of the dialogue is Morgan, whom the Brewers acquired in a trade from the Washington Nationals during spring training, and who has energized their clubhouse with his personality, flair and multiple alter-egos.

“The game is not so black-and-white anymore,” Morgan said. “It’s more colorful.”

Perhaps that is true of the Brewers, but for the most part the Cardinals are perfectly content with black and white. None of them cared to revisit the Sept. 7 near-brawl. “I don’t even think about it,” Cardinals slugger Albert Pujols deadpanned. “When did that happen? I don’t even remember when that happened.

But the Cardinals, of course, remember it well, and it seems plausible they might try to set Morgan off again, in hopes he will do something outlandish that could get him suspended. Morgan acknowledged as much, saying he fully expects the Cardinals to “try to get under my skin.”

“I might have to wear one, I don’t know,” Morgan said in reference to a possible outbreak of beanballs. “I don’t really see it going that far. I don’t think anybody needs to do anything to [subject themselves to possible suspensions]. It’s just going to be a hard-fought battle with two teams getting after it.”