"You don't want to walk them, because everybody yells at you when you walk them with a four-run lead," Dempster said. "Then you give up a home run, and they're like, 'What are you doing?' It's a catch-22."
Dempster has a 3.72 ERA (12 earned runs over 29 innings) in 29 save situations, compared to a 4.70 ERA (16 earned runs in 30 2/3 innings) in 29 non-save situations.
Dempster wasn't happy after Friday's outing. The Cubs did hold on for a 5-3 win over the St. Louis Cardinals, but the outing didn't help Dempster's numbers this month. He is 0-2 with a 10.57 ERA in eight games in September with three saves.
"You just have to be better than that," Dempster said of Friday's outing.
Does it make a difference if it's a save situation or not?
"It's that way with a lot of closers," Cubs pitching coach Larry Rothschild said. "When you get to this point in the year, you hope that doesn't matter. The importance of winning the game is magnified quite a bit.
"Whether it's a save situation or not, you should get the adrenaline going," Rothschild said. "It was one of those nights, and we need to bounce back today. Hopefully, he gets a good inning today."
Dempster, who has 26 saves, was prepared to pitch in both games of Saturday's day-night doubleheader.
"I'll be ready every day," Dempster said.
"He's human, and you go through different things," Rothschild said of the Cubs closer. "I thought before the injury [before the All-Star break], he was throwing as well as I've seen him throw it in the whole time here. He was really on his game.
"It's unfortunate, when he had the abdominal strain and the oblique, that it took a while for him to get back on it," Rothschild said. "Then, he got on a nice little run, and hopefully, we can get on a run now for the last 15 [or] 16 games."
Dempster did convert 13 straight save opportunities in a streak that ended Sept. 6 against Los Angeles.
"Dempster is a good pitcher for us; he's been doing a good job for us," Chicago pitcher Carlos Zambrano said. "He's human, too. The good thing about it is, I know Dempster, and he'll come back and be ready to save a game for us."
The Cubs are watching their relievers closely for the final 15 games.
"If we have the opportunity to get guys rest, we'll do it," Rothschild said. "We're going to use them -- there's no such thing as rest now, unless it's something that can easily be accomplished."
Good student: Carlos Marmol has impressed the other Cubs relievers not just with his fastball and slider, but also his eagerness to get better.
"He asks questions," Cubs lefty Scott Eyre said. "He wants to learn."
Marmol has quizzed them about when to warm up and how to handle certain situations and hitters.
"They're experienced guys, and they know what to do," Marmol said.
After pitching a scoreless inning on Saturday against the Cardinals, Marmol now has a 1.29 ERA and has held opponents to a .169 batting average.
"He's got confidence in himself," Cubs rookie catcher Geovany Soto said of Marmol. "You come up here and you try to prove yourself in a certain way to get the ball, and he's done that. Now, he's got confidence in himself, and he's the guy now."
Double or nothing: Saturday's doubleheader is the fourth day-night twin bill in the last 40 seasons for the Cubs. The last one was July 7, 2005, at Atlanta, and they lost both games.
Saturday was the Cubs' first doubleheader in St. Louis since June 8, 1992, which the Cubs swept.
Extra bases: Sean Marshall, the Game 2 starter, got a head start on Saturday. He arrived at the ballpark at 10:30 a.m. -- and his game wasn't to start until 7:10 p.m. ... Marshall and lefty Ted Lilly started on Saturday. The last time the Cubs used two lefties for both games of a doubleheader was July 29, 1986, at New York. Steve Trout took a 3-0 loss in the first game, and Jamie Moyer won the second game, 2-1. ... The last time the Cubs swept a twin bill using two lefty starters was June 19, 1966, against Houston. Dick Ellsworth and Ken Holtzman were the winners. ... The Cubs entered the weekend looking for their 10th win against the Cardinals this year. If they get it, it would be the third straight year with 10 wins in the season series. ... Zambrano's next start will be Tuesday, and he'll be pitching on short rest.
"I always say I'm sure I can pitch with three days' rest all the time," Zambrano said. "I feel better with less days of rest than five or six days."
On deck: Jason Marquis will close the season series on Sunday, facing Mark Mulder at Busch Stadium. First pitch is slated for 1:15 p.m. CT and the game will be broadcast on WGN.