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The Houston Astros remain in contention in the NL wild card race, but injuries are threatening to hurt their chances unless they can continue to get contributions from everyone on the team.

The Astros open a four-game series on Monday against the Pittsburgh Pirates, who have dominated Houston despite their struggles this season.

The Astros (76-67) are 2-7 against Pittsburgh (60-82) this season, although the Pirates are just 28-40 against the NL Central. Houston, however, comes in having won 10 of 11, which has moved it back into postseason contention. With 19 games remaining, Houston is in fourth place in the wild card standings, six games behind the Milwaukee Brewers.

Houston won two of three against the Colorado Rockies over the weekend, including a 7-5 victory Sunday, but it has several injury concerns as it tries to continue its recent run.

Ty Wigginton, who hit .379 with 12 homers in August, is expected to miss 10 games after injuring his left hamstring running out a groundball on Saturday night. Then on Sunday, Astros starter Wandy Rodriguez left in the second inning with a left oblique strain, which came after it was announced that Brandon Backe, who was scheduled to pitch Monday, had his start pushed back because of tightness in his surgically repaired right elbow.

Houston is trying to remain positive, though, after Sunday's come-from-behind win. Pinch-hitters Darin Erstad and David Newhan had back-to-back run-scoring hits in the eighth and Jack Cassel threw four solid innings after Rodriguez left the game.

"I went down the stinkin' lineup, and I think everybody contributed something. Everybody did," manager Cecil Cooper said.

Right-hander Alberto Arias (0-0, 2.63 ERA) will pitch in place of Backe on Monday in his first major league start.

Arias was acquired off waivers from the Rockies on July 31. He is 1-0 with a 3.43 ERA in 18 appearances over two seasons with Colorado. In 12 relief appearances this season, he's allowed four runs and 12 hits in 13 2-3 innings of work.

Ian Snell (6-10, 5.59) counters for the Pirates.

Snell is 2-1 with a 3.13 ERA in his last four starts. He pitched six innings last Tuesday to beat Cincinnati, allowing two runs -- one earned -- in a 3-2 victory.

The right-hander is 0-0 with an 8.10 ERA in two starts against the Astros this year.

The Pirates have lost 13 of their last 16, including two of three to the San Francisco Giants over the weekend.

Nate McLouth is considered day-to-day after he suffered a cut above his left eyebrow that required six stitches in Sunday's 11-6 loss.

Sunday's loss guaranteed the Pirates will finish with a losing record, matching the Philadelphia Phillies' 1933-48 major league record for consecutive losing seasons at 16.

"Nobody is happy with the record," manager John Russell said. "Nobody is happy with losing. We're putting in a lot of work and we're making progress. It's just not equating to wins right now."