Bud Norris turned in his best performance of the season with eight innings of one-run ball, Lance Berkman continued his resurgence with three hits and an RBI and Hunter Pence hit a three-run homer in leading the Houston Astros to a 4-1 victory and a three-game sweep of the St. Louis Cardinals on Thursday.

The Astros have won four straight, all against first-place teams. Houston improved to 12-3 when it scores four or more runs -- it is 1-18 when it scores three or fewer.

The Astros didn't need to score much for Norris (2-4), who reined in the control problems that have plagued him this season. He didn't walk a batter and allowed only six hits while striking out eight.

Matt Lindstrom worked around a two-out walk in the ninth for his ninth save in as many tries. He earned saves in all three wins of the series.

Houston took a 4-0 lead against Cardinals starter Chris Carpenter, scoring all four in the third inning on Berkman's RBI single and Pence's three-run homer. It was Pence's fifth homer of the season and his second in the series.

Carpenter (4-1) allowed the four runs on six hits and three walks in eight innings.

St. Louis has lost seven of nine and its lead in the NL Central is down to a half-game over Cincinnati, which plays host to the Cardinals for a three-game series starting Friday.