HOUSTON -- The Astros activated infielder Chris Johnson from the 15-day disabled list Saturday and assigned him to Triple-A Round Rock.

Johnson had been placed on the DL on April 20 with a strained right intercostal muscle. He spent the last three days rehabbing at extended spring training in Kissimmee, Fla.

Johnson, who hit .227 in eight games with Houston, is not expected to rejoin the Astros soon.

"Our goal is to play him as much as we can [in Triple-A] until we've got a need up here," general manager Ed Wade said Saturday.

Astros try to keep closer Lindstrom sharp

HOUSTON -- Astros closer Matt Lindstrom had six saves entering Saturday night's game against the Padres, which is more impressive considering Houston entered with only nine wins. He appeared in just 12 of the club's first 29 games.

"It's a matter of trying to stay sharp, trying to stay consistent," said Lindstrom, who spent the last three seasons with the Marlins. "I think hitting's the same way, though I can't speak for the hitters, since it's been 10-plus years [since I've hit]. When you do feel a little better than normal, more excited, I try to tone it down. I try to stay on even level. Sometimes it's hard. If you've had three or four days off, you don't want to do too much."

There hasn't been enough work for Lindstrom in Houston, which is last in the National League in runs scored by a wide margin.

"It can be tough if you think about it too much," said Lindstrom, who hasn't blown a save this season. "You just have to stay ready. We have a lot more games. There's going to be opportunities."

Lindstrom earned the win, his first decision of the year, on Wednesday night against Arizona, pitching a scoreless top of the ninth before Carlos Lee hit a two-run homer in the bottom of the inning to win it.

"Wins aren't really important to me," Lindstrom said. "I like [coming into games] better when we're ahead."

"We're not going to save him for [save-only situations]," manager Brad Mills said. "He needs to stay sharp."

Berkman has been down this path before

HOUSTON -- Astros slugger Lance Berkman has been down the road of slow starts before. He said of the 10 years he has begun the season with Houston, he stumbled out of the gate five times. He said there is no formula for why or even how to turn it around.

The 34-year-old Berkman, who entered Saturday's game hitting .185, is smart enough not to start tinkering with his stance or his swing.

"Not at this point of my career," he said. "If this was the first time I had been through it in my career, then maybe. With the experience piled under my belt, I'm not the least bit concerned."

Berkman underwent arthroscopic surgery on his left knee March 13 and missed all of Spring Training. He missed the first 12 games of the regular season before being activated April 20.

"I think I'm just now having as many at-bats as I would during a normal Spring Training," he said. "It's hard to walk in cold turkey and expect to compete at the Major League level. That's just a very difficult thing to do.

"In '05 [after undergoing knee surgery in November 2004], my first game was May 6 or 7, I had no Spring Training, and I struggled for two months. I ended up with a decent year for having missed a month."

Berkman remembered his tough beginning in 2007, when he had one extra-base hit the first two months of the season, but ended up with 34 homers and 102 RBIs.

"It's always frustrating when you're not swinging the bat -- even if it's 10, 12 at-bats," he said. "Either it's going to turn around or it's not. If it doesn't, I'll find something else to do. But I fully expect that it will [turn around]."

Mills swaps Lee, Berkman in batting order

HOUSTON -- Astros manager Brad Mills made some adjustments to his lineup before Saturday night's game with the Padres.

Mills switched Carlos Lee and Lance Berkman in the order, moving Berkman up to third and dropping Lee to the cleanup spot.

"I think the first time we did it, we scored five runs against the Pirates and the next day we scored 10 runs with Lance hitting fourth," Mills said. "That was pretty good, but I think now it's run its course. We'll flip them back and see if there's any significance there and if anything happens."

Mills also gave shortstop Tommy Manzella the night off, starting Jeff Keppinger at short and leaving Kazuo Matsui at second base.

"Kaz is starting to swing the bat better," Mills explained of starting Keppinger at short instead of his normal position at second.

"With those three guys, if we can keep moving them around a little bit, I think it's going to be better for all three of them and better for us."

Chacin impresses after long layoff

HOUSTON -- Left-hander Gustavo Chacin pitched two innings of scoreless relief in Friday night's 7-0 home loss to the Padres.

The game marked Chacin's first appearance in the Majors since April 28, 2007, when he pitched for Toronto. He started five games for the Blue Jays that season, going 2-1 with a 5.60 ERA, before experiencing problems with his left shoulder.

In 2005, he went 13-9 with a 3.72 ERA in 34 starts for Toronto.

Friday's game was his first relief appearance in the Majors.

"He's had success at the big league level," Astros manager Brad Mills said. "I was there to see that first-hand [as a coach with Boston]. We know it's there. He did a real good job in winter ball. He had some success at times in Spring Training. It's nice to see another guy come out of that 'pen and give us some scoreless innings."

Chacin began the season at Triple-A Round Rock and went 1-1 with a 3.65 ERA in five starts before being called up on Monday to replace injured left-hander Tim Byrdak in the bullpen.