PITTSBURGH (AP) -- Jeff Locke allowed three hits over seven innings, Pedro Alvarez homered and the Pittsburgh Pirates won for the eighth time in 10 games, 1-0 over the Houston Astros on Sunday.

Locke (4-1) won his fourth straight decisions and gave up one run or fewer for the fifth time in his past eight outings. He struck out four and walked three.

The notoriously streaky Alvarez pushed his average above .200 for just the second time since the second game of the season. His eighth home run came on the first pitch and was an opposite field line drive down the left field line in the fifth.

Alvarez's longball was his second of the series and third in eight games. It was the lone mistake by Astros starter Lucas Harrell, who lost his third consecutive decision despite allowing four hits and one walk in seven innings.