Both teams are hot. The Brewers have already swept the Cubs and Astros to begin a long homestand and are 11 games over .500 for the first time in more than two years. The Cardinals have won seven of their last 11 games.
As of midday Sunday, the Brewers had already sold at least 35,000 tickets for each of the three games and were expecting crowds of 40,000-plus on Monday and Wednesday.
"I think everybody's excited," Brewers first baseman Prince Fielder said. "Usually, when you're excited to come to the field, it means you have a good team and everybody is just trying to keep it going. We're in a good position now, but there's still two months left in the season and we've got to keep it going."
The Cardinals are trying to do the same in the first meeting between the teams since early June.
Then the Cardinals were in first place, 2 1/2 games ahead of the Brewers. After Milwaukee's three-game sweep, the Brewers were in first place for the first time this season.
"They're on a pretty good winning streak right now, they're going to be fired up, and for us to go in there and win that series is key," Cardinals third baseman David Freese said. "You've got to beat the teams that you're contending with to win the division. Going in there in the next few days and grabbing some victories is going to be huge."
The Brewers get to feature both of their big offseason acquisitions. Greinke will pitch the opener, and fellow right-hander Shaun Marcum will work the second game on Tuesday night against Cardinals lefty Jaime Garcia.
The Cardinals will showcase their own rotation newcomer in Wednesday's finale. Right-hander Edwin Jackson, acquired last week in a Trade Deadline blockbuster from the Blue Jays, starts against Brewers lefty Randy Wolf.
"Once you start getting into August, it's crunch time," Freese said. "The Deadline is up and both teams made some moves, and I think both teams are excited with where they're at, so it's definitely going to be a battle."
"We'd probably like to have a bigger lead, but it's going to be a lot of fun these last two months," Marcum said. "We've gotten some guys who can help us out, and St. Louis has, too."
The Brewers' big July trade was for reliever Francisco Rodriguez, but they also added Felipe Lopez and Jerry Hairston Jr. for infield depth.
The Cardinals made a pair of "win-now" deals, acquiring Jackson, outfielder Corey Patterson and bullpen help from Toronto and then shortstop Rafael Furcal from the Dodgers. Furcal will probably make his first Cardinals start on Monday night.
"You always want to treat every game the same, but subconsciously it will be somewhat of a playoff-atmosphere-type feel," said Patterson, who played briefly for the Brewers in 2009. "It will be exciting, and it's only going to help for the latter part of the season. It will be able to help the guys who haven't experienced this so much."
One of those guys on the Brewers' side is Greinke, who said he's excited to pitch in his first true pennant race. But Greinke pointed out that he's pitched meaningful games for the Royals, who have been positioned to play spoiler late in recent seasons. Greinke pitched the next to last game of his sensational 2009 season against a Twins team that fought down to the wire against the Tigers. In his final start of 2010, Greinke beat the Rays to leave them tied with the Yankees atop the American League East with three games to play.
He knows the Twins well after so many years in the AL Central and has compared them before to the Cardinals. Both teams always seem to get the most out of their talent, Greinke said, and tend to play meaningful games all the way to the end.
"So what he's saying is come talk to him on like Sept. 18," said outfielder Mark Kotsay, who dresses next to Greinke.
"Even then, you still can't predict it," Greinke said.
Both players understand the hype generated by this week's series. And they understand that, barring a tank from either team, it will resurface when the Brewers travel to St. Louis from Aug. 9-11 and Sept. 5-7, and when the Cardinals return to Miller Park from Aug. 30-Sept. 1.
The Pirates and Reds make it a four-team race for now.
"Once you find out which teams are 'in it,' clearly, it's important to beat them," Brewers third baseman Casey McGehee said. "But if you beat St. Louis, Pittsburgh, Cincinnati and then you turn around and lay an egg against a team that's not 'in it,' you didn't gain anything. That's where it's hard to say a series is hugely important.
"Because, for whatever team loses this series, what do you do afterward? Are you supposed to be demoralized?"
That will not happen. Not with two months to play.
"It's pretty neat, because I looked at our schedule and it seems like I'm pitching against the National League Central the rest of the season," Greinke said. "I know these are some important times."