HOUSTON -- For now, right fielder Tyler Colvin is content batting eighth in the Cubs' batting order, despite his recent power surge, which includes a home run on Tuesday.

Colvin, who popped out to the catcher in his first at-bat, had three extra-base hits in his past four games entering Wednesday.

"I don't care where I'm at as long as I'm in the lineup," said Colvin, who is in his third stint with the Cubs this season. "In the eight-hole, you got the pitcher behind you. You know they're always trying to pitch around you. All in all, I don't mind it. It's a spot in the lineup."

A first-round pick by Chicago in the 2006 First-Year Player Draft, Colvin had 20 homers in 358 at-bats with the Cubs last season.

"I don't consider myself a home run hitter," said Colvin. "I just go up there and hit the ball hard, and if it goes out, great.

"But I can't be thinking about hitting home runs. I worry about getting ready on time and hitting the ball hard. Whatever happens after that, happens."

Quade will keep close tabs on Marmol

HOUSTON -- Cubs manager Mike Quade feels that closer Carlos Marmol's velocity is diminished, and he'll continue to monitor the reliever closely.

On Tuesday, Marmol gave up a pinch-hit, walk-off grand slam to Brian Bogusevic with one out in the ninth inning of a 6-5 loss.

It was the right-hander's eighth blown save, snapping a stretch of nine consecutive saves. On Tuesday, after retiring the first batter he faced, Marmol loaded the bases on a pair of singles and a walk, before Bogusevic's blast to left-center.

"I think his velocity is down some this year," said Quade. "And during his real tough time, his slider wasn't sharp. We'll keep a close eye on Marmol like we do all of them. Recently, he's been good."

Command has always been a come-and-go thing for Marmol, whose 296 relief appearances since the start of 2008 are most in the Major Leagues.

"It's an ongoing thing," said Quade. "He's had a wonderful run here. This is the first real adversity he's had in his career."

Because Marmol (2-4, 4.08 ERA) is so unorthodox mechanically, sometimes it's tough to keep him in top form.

"Whether it's arm angle, whether it's stride, whether it's driving off the back of the rubber," said Quade, "all the stuff that makes him who he is -- especially with so much deception that he does to go along with the slider ... he normally shows up with -- also makes it tough to get him untracked."