A pair of struggling teams meet tonight in Pittsburgh, as the Houston Astros open a three-game series against the Pirates at PNC Park. The Astros have lost three in a row and Pittsburgh is in the midst of a four-game skid. Houston dropped the final three tests of a four-game series in Washington. In Wednesday`s finale, Jose Vidro hit a home run and had four runs batted in to lead the Nationals to an 8-5 victory. Houston starter Andy Pettitte (3-6) was tagged for seven runs on eight hits in just three innings of work in his sixth loss of the season. Preston Wilson finished 4-for-5 with an RBI and two runs scored for the Astros. The Pirates were swept in a three-game series in Arizona, with the Diamondbacks earning an 8-7 win in Wednesday`s finale. Craig Wilson was 4-for-5 with a home run and Jason Bay went 2-for-4 with three runs batted in and two runs scored for Pittsburgh, which has lost six of its last seven contests. Zach Duke (2-6) was collared with the loss after surrendering five runs - four earned - on nine hits with no walks and five strikeouts for the Pirates. Taylor Buchholz hopes to keep the momentum going from the best start of his young career as he takes the ball for the Astros tonight. Buchholz had been pounded for eight runs in consecutive outings, but turned things around with last Sunday`s shutout of the Texas Rangers. He surrendered just five hits over his nine scoreless innings and struck out six batters without walking anyone. The rookie right-hander faced Pittsburgh once earlier this season and picked up the victory with 8 2/3 scoreless innings. Ian Snell will try to win back-to-back starts tonight when he counters tonight for Pittsburgh. Snell earned a victory last Saturday in Cleveland after allowing five runs - two earned - in five innings of work. He struck out four and walked a season- high five batters. The 24-year-old right-hander is 1-2 with a 3.00 ERA in four career games (three starts) against the Astros. The Astros swept Pittsburgh at Minute Maid Park from April 21-23 and are 34-18 in the series since the start of the 2003 campaign.