Cubs manager Dusty Baker keeps throwing out little warning signs for his team.
The latest, now that they are in a stretch of 19 straight games against NL Central Division opponents: If you don't win in your own division, you might not make the playoffs.
"One thing [the Astros] have done the last couple of years, they've been extremely tough in their division," Baker said.
After Sunday night's dramatic 4-3 victory over the Cardinals, the Cubs have won 11 of 19 games against Central teams, compared with 15 of 25 for Houston and only eight of 20 for the Cardinals.
With the success in front of 40,090 fans on a summerlike night at Wrigley Field, the Cubs won two of three from their fiercest rivals and lead the season series 4-3.
More important, they stayed tied for first in the Central Division, although it is not with Houston or St. Louis. The surprise co-leaders are the Cincinnati Reds, who are 4-3 against the Cubs.
And next comes a two-game series in Houston.
"It's important for us to beat the Cardinals, especially with what I've heard that the last 10 years the Cardinals have pretty much had their way with the Cubs," Baker said. "I understand Houston has too.
"If we're going to get on this run of excellence, we're going to have to beat the Cardinals, and we're going to have to break the Astros."
If Matt Clement pitches like he did Sunday night, the Cubs will get their share of big victories. The right-hander survived seven strong innings despite battling asthma and a recent bout of flu.
LaTroy Hawkins pitched a perfect eighth inning, and then Joe Borowski saved his eighth straight game this season by retiring Albert Pujols, Jim Edmonds and Scott Rolen, who had combined for 32 homers this season.
"It was big to win a series against these guys," Clement said. "Anytime you do that against this team that has given us trouble in the past I can't say enough about my team. They got me those runs early, and Hawkins and Borowski were super."
Cardinals starter Matt Morris came into the game 10-2 lifetime against the Cubs and 5-2 at Wrigley Field, so Baker didn't take any chances. He sat right fielder Todd Hollandsworth, who had homered the day before, and started Tom Goodwin, who had been 5-for-10 against Morris in his career.
And guess what? Goodwin ignited the Cubs' four-run first inning with a leadoff single.
Goodwin and Moises Alou, who had singled, scored when Aramis Ramirez mailed a Morris pitch into the left-field bleachers. The final first-inning run came when Derrek Lee walked and Michael Barrett doubled.
A few days ago, Baker had described Ramirez as "the RBI man," something in which the third baseman takes pride.
"That's what I get paid for, to drive in runs," Ramirez said.
The four-run first took Clement off the hook for the run he had allowed in the top of the inning when he issued back-to-back walks in front of Rolen's single.
The Cardinals closed to 4-2 in the sixth when Pujols, the defending NL batting champion who has been quiet this series, crushed a Clement pitch deep into the night to left field.
And they made it 4-3 in the seventh when Rolen also took a tiring Clement deep.
"He said, 'I don't want to come out,'" Baker said, "but that's all he had. He made pitches when he had to."
Of course, these being the Cubs, no victory comes without a warning sign pointing toward the trainer's room. The latest possible casualty is Hawkins, who made it through his inning without hurting himself.
"He said [his arm] had been a little tender," Baker said.
"We've got a long way to go, and we certainly don't want to lose Hawk."