(Best E Casino) - The Arizona Diamondbacks' recent weekend series did nothing to clear up a tight National League West race. Tonight the club will try to beat up on one of the worst road teams in the league as it begins a three-game series with the Pittsburgh Pirates at Chase Field.

Arizona returns home for seven straight games after going 7-3 on a recent 10- game road trip. The swing ended with four straight tests versus the Los Angeles Dodgers, which entered the series trailing the Diamondbacks by one game. Arizona won the first two games of the set but dropped the last two tests.

Arizona's offense struggled in Los Angeles, as the club failed to score more than three runs in any of its games versus the Dodgers over the weekend. It lost Sunday's finale, 9-3, getting three hits -- including a homer -- and two RBI out of Stephen Drew.

The Diamondbacks might be able to get away with another poor offensive showing tonight, as Dan Haren is set to take the hill. Haren is 11-5 with a 2.62 earned run average on the season, with Arizona winning nine of his last 11 starts.

Haren himself has posted a victory in each of his last three outings, defeating San Diego on Wednesday after giving up three runs on seven hits with six strikeouts over seven innings. Haren now returns to Chase Field, where he is 8-2 with a 2.20 ERA in 11 starts this season.

The 27-year-old right-hander is 2-0 in four career starts versus Pittsburgh, posting a 2.96 ERA in that span. He didn't factor into the decision of a start against the Pirates on June 7 in Pittsburgh, allowing three runs on five hits over seven innings. Jason Bay and Nate McLouth homered off Haren in that test.

Bay, though, is no longer on Pittsburgh's roster, as he was part of a three- team trade that sent Manny Ramirez to Los Angeles and Bay to Boston. The Pirates received four players in return from those clubs, and three of those players factored into Sunday's 8-5 setback to the Cubs.

Andy LaRoche and Brandon Moss each hit their first home runs as members of the Pirates. LaRoche began the season with the Dodgers, while Moss came over from the Red Sox. Craig Hansen was also part of the package Boston sent to the Steel City, and he took the loss on Sunday after getting charged with the decisive run in 1 2/3 innings of work.

Pirates second baseman Freddy Sanchez was out of the starting lineup for the sixth straight game due to lower back spasms, but did strike out as a pinch- hitter in the ninth inning.

The loss dropped the Pirates to just 1-2 on their 10-game, four-city road trip. Pittsburgh is a mere 19-34 as the visiting club this year and its team ERA of 6.30 on the road is the worst in the majors.

Perhaps fresh blood can alter that trend. Yoslan Herrera makes just his fifth career start tonight, with the Pirates having gone 3-1 over his first four outings. Herrera himself got a no-decision on Tuesday versus the Rockies, allowing four runs on six hits over five innings.

The 27-year-old right-hander makes just his second career road start after posting his first big league loss on July 19 in Colorado. He followed that up with his first career win, defeating San Diego on July 24.

The Diamondbacks and Pirates split four games in Pittsburgh earlier this year.