Jeff Karstens scattered four hits over eight innings and the surging Pittsburgh Pirates blanked the Houston Astros 2-0 on Thursday night.
Karstens (2-2) struck out a season-high eight against just one walk as the Pirates completed their first four-game sweep of the Astros at home since 1979. Joel Hanrahan pitched a perfect ninth for his 22nd save.
Garrett Jones and Casey McGehee each drove in a run for Pittsburgh, which has won eight of nine to vault into first in the National League Central.
Houston's Bud Norris (5-6) gave up two runs and five hits in seven solid innings but the Astros' offense sputtered a day after trading slugger Carlos Lee to the Miami Marlins. Houston managed four singles while losing its eighth straight game.
(Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)