© 2010 MLB Advanced Media, L.P. All rights reserved.

10/12/10 2:14 AM ET

In clincher, Giants' bullpen shows dominant self

ATLANTA -- The Giants' bullpen returned to form on Monday night.

And because their starting pitching -- in this case, Madison Bumgarner -- remained effective, the Atlanta Braves would be challenged to score.

Indeed, the Giants won yet another low-scoring one-run affair, defeating the Braves, 3-2, in Game 4 of the National League Division Series. San Francisco subdued Atlanta, 3-1, and advanced to the NL Championship Series against Philadelphia, starting on Saturday on FOX.

The Giants did it with considerable help from their bullpen, as Santiago Casilla, Javier Lopez and closer Brian Wilson blanked Atlanta over the final three innings.

Though San Francisco's starters -- namely Tim Lincecum, Matt Cain and Jonathan Sanchez -- combined to record an 0.39 ERA (one earned run in 23 innings) in the series' first three games, the bullpen's ERA stood at 6.00. Sergio Romo, the Giants' top setup man, had endured a particularly rough time by allowing three runs in two-thirds of an inning.

Manager Bruce Bochy said of Romo before Monday's game: "I still believe in this kid, because he's a big reason why we're here."

So is Casilla, the first Giants reliever to appear Monday with San Francisco clinging to a 3-2 lead. He worked a dominant seventh inning, striking out Diory Hernandez before inducing two comebackers. Catcher Buster Posey pointed out that Casilla embodies the talent as well as depth in San Francisco's relief corps.

"You got a guy like Casilla, coming [in] in the seventh inning throwing 98 [mph], and his ball's moving three feet -- that should say something about our bullpen," Posey said. "They've been lights-out over the past month."

Casilla gave the ball to Lopez, with pinch-runner Nate McLouth on second base, two outs and NL Rookie of the Year Award candidate Jason Heyward at bat. Since acquiring Lopez from Pittsburgh on July 31, the Giants used him to neutralize left-handed batters, who went only 5-for-45 against him after he joined San Francisco. Lopez did his job again by striking out Heyward, who went 2-for-16 in the series.

That left Wilson, who walked Rick Ankiel and Eric Hinske with one out in the ninth, but he notched his second NLDS save by striking out Omar Infante and retiring Melky Cabrera on a grounder to third base.

"I've had runners on first and second with one out before," Wilson said. "To me, it's just as important on June 2 as it is now. Losing any game when you're up, it's a crappy flight. It's not fun, going from East Coast to West Coast after having the game in the palm of your hand and blowing it."

Chris Haft is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.