CHICAGO -- Chris Sampson doesn't have a ton of Major League experience, but if he's trying to make a case for making his presence in the starting rotation permanent, perhaps he should face the Chicago Cubs more often.

Sampson shut out the Cubs on Tuesday during a five-inning performance that led the Astros to their second consecutive win over their division rival, 4-2, before 35,924 at Wrigley Field.

Dating back to June 7 of last year, Sampson has thrown 12 scoreless frames against the Cubs, spanning two starts. And the 28-year-old has only made four big-league starts in his career.

Sampson scattered three hits, walking one and striking out three. He threw only 64 pitches but left the game with a slight tweak in his left calf muscle, which he suffered while running out of the batter's box during his at-bat in the fourth inning.

Sampson stayed in long enough to record six more outs, but considering the cold climate in Chicago this time of year, manager Phil Garner thought it was best to take him out while the damage was still minimal.

"Coming out of the box, it grabbed him pretty good," Garner said. "He could pitch, but when he had to cover first base the next inning, it bothered him. I felt like he might be taking a chance on blowing it out so I took him out."

Sampson's outing was short, but memorable. Working with an immediate 3-0 lead, helped by Luke Scott's two-run double in the first inning, Sampson recorded five groundball outs and allowed only one baserunner to reach second.

"I just pitched my game and let my defense help me out," Sampson said. "Throw strikes, and it really helped out that we got three runs in the first inning. I could really concentrate on throwing strikes and let my defense help me out."

"He did what he does best," catcher Brad Ausmus said. "He has late movement on all his pitches, and he keeps the ball down in the zone where he can get ground balls."

With such a short Major League track record, Sampson had to fight for a starting spot just like everyone else during Spring Training. The small sampling he offered in the prior season was impressive, without a doubt, but with only 34 innings of big-league experience, the Astros weren't ready to hand Sampson a starting job.

He didn't make many starts during the exhibition season, but other than one rough outing, he was convincing enough to merit a starting spot when the rotation was announced two days before the opener.

"I feel like he can take us deeper in the ballgame. And he doesn't beat himself."

-- Garner, on Sampson

Tuesday's performance, although a couple of innings too short, was precisely why Garner thought Sampson was worthy of the fifth starter spot.

"He's efficient," Garner said. "I feel like he can take us deeper in the ballgame. And he doesn't beat himself. He's going to throw the ball over the plate."

"I definitely wanted to get out to a good start," Sampson said. "Everybody that was in Spring Training that was competing for the No. 4 and No. 5 spots did really well. I just want to continue to do well and keep my spot in the rotation."

Sampson is penciled in to make his next start on April 17, which would give him two extra days of rest. Both he and Garner are confident his calf injury will not force him to miss that home start against the Marlins.

The bullpen took over in the sixth. Rick White extended his scoreless streak to 5 1/3 innings with two perfect frames, followed by a smooth eighth inning from Chad Qualls.

Dan Wheeler allowed two runs in the ninth and brought the winning run to the plate with two outs, but Matt Murton popped out to Lance Berkman to end the game.

"It was a little bit nerve-racking," said Garner, who had Brad Lidge warming in the bullpen. "You know the Cubs are going to hit. You just hope they don't put it together all in one inning.

"The colder weather makes it a little bit tougher because you don't have a feel for the ball sometimes. Your hands get slick and you're not able to control the ball. Wheeler is a control pitcher. I thought we got a couple strikes on guys and he missed on his location, which is not typical for him."

"With a four-run lead, you don't want the tying and winning run to come to the plate," Wheeler said. "That's the last thing you want. To get out of that with a win was awesome."