Don Mattingly wants to get the Dodgers back into the NL West race one step at a time. First goal: get back to .500.

But that is turning out to be a difficult challenge for the rookie manager and his injury-riddled club. Saturday night's 7-0 loss to Wandy Rodriguez and the lowly Houston Astros put Los Angeles 10 games under .500 for the first time since 2005, when the team finished 71-91.

The Dodgers have dropped five straight and eighth of 10. Their six-game home losing streak is their longest since a six-game stretch in August 2007, and they trail San Francisco by 8½ games.

"I'm not so much worried about where we're at, as far as games back. My biggest fight is for us to get back to .500, and we've got to get there as quick as possible," Mattingly said. "The short-term goal for us is to get back to .500 before the (All-Star) break. We have to do that before we can even talk about worrying about the teams in front of us."

Rubby De La Rosa (3-1) was charged with five runs, six hits and three walks over 4 2-3 innings and struck out six in his third major league start. The 22-year-old right-hander, inserted into the rotation because of Jon Garland's inflamed right shoulder, won his previous two outings on the road against Philadelphia and Colorado and pitched five innings each time.

"We're not at the end of the first half of the season yet, so I think we still have a chance," De La Rosa said through a translator. "I think we all feel that way."

De La Rosa held the Astros to just two hits over the first four innings, striking out the side on 14 pitches in the second. But the Astros broke through for five runs in the fifth to break a scoreless tie after loading the bases with none out.

Carlos Corporan and Rodriguez struck out before De La Rosa walked Michael Bourn to force in a run. Jason Bourgeois singled off the glove of first baseman Casey Blake to drive in another run and Jeff Keppinger added a two-run single.

De La Rosa then walked Carlos Lee and was replaced by Mike MacDougal, whose wild pitch to Brett Wallace allowed Bourgeois to score the fifth run. Rod Barajas scrambled after the ball and sprained his right ankle popping back up to his feet. He limped back to the dugout and was replaced behind the plate by Dioner Navarro.

Rodriguez (5-3) scattered seven hits over six gritty innings, struck out six and was lifted after 103 pitches in his second straight scoreless start since coming off the disabled list.

The left-hander is 4-0 with a 1.29 ERA over his last seven starts. Last Monday, he gave up just two hits over six scoreless innings after missing 19 games due to elbow problems.

The Astros, coming off Brett Myers' complete-game, 7-3 win on Friday night, have won consecutive games for the first time since winning four in a row May 30-June 2 after entering this three-game series in a 2-11 skid with the worst record in the majors.

Right fielder Hunter Pence was scratched from manager Brad Mills' original lineup because of a hyperextended left elbow. The injury occurred in Friday's game, when he hit a grounder to first base and dived into the bag trying to avoid James Loney's tag.

Bourgeous filled in for him and threw out Barajas at home plate in the second inning when he tried to score on a single by rookie Dee Gordon.

"With two outs early in the ballgame, I guess they wanted to take a chance," Bourgeois said. "I just came up throwing, like he's running every time and just tried to make an aggressive throw. I'm just glad Corporan hung in there. That was a big man sliding into home."

Pence, who came in with the NL's fourth-highest batting average (.321), is scheduled to fly back to Houston Sunday morning for an MRI and then rejoin the club for a road series against the Texas Rangers.

Pence does not want to miss the next series, because Arlington, Texas is where he played his high school and college ball. In 11 big league games there, he is 15 for 46 with six RBIs and three home runs — all solo shots.

"I just want to get it checked out so that we know exactly what it is," said Pence, who had a 23-game hitting streak that ended on Tuesday. "I wasn't able to play tonight, but I'm hopeful I'm going to be back for the Rangers series. I feel confident. In my heart, I feel like it's just swollen."

NOTES: Andre Ethier, who homered in the ninth inning of the Dodgers' 7-3 loss Friday night, doubled his first time up against Rodriguez. It's only the second time all season that he had extra-base hits in consecutive at-bats. The other time was April 16 against St. Louis, when he doubled in the sixth and eighth innings. ... The Dodgers reinstated RHP Kenley Jansen from the 15-day disabled list and optioned RHP Josh Lindblom to Double-A Chattanooga. ... Blake was in the starting lineup for the first time since June 10 and was 1 for 4 with two strikeouts. He had five at-bats between then and Saturday with one hit, a go-ahead three-run double against Colorado's Matt Reynolds.