The Astros have won 10 of 11 and have moved within 2 1/2 games of the Chicago Cubs, the NL wild-card leader.
The Astros have won six straight games, scoring at least seven runs each time. They have hit 14 home runs and scored 36 runs over the last four games.
The Astros could have had five homers, but Pirates right fielder Rob Mackowiak robbed Beltran of a homer in the first, leaping high to snatch away the ball just as it reached the fence.
Beltran is batting .270 with 22 home runs, 22 stolen bases and 47 RBIs in 62 games since getting traded from Kanas City to Houston in July. The All-Star outfielder has 37 homers and 36 stolen bases total in 131 total games this season.
Houston will try to continue its home run tear against Pittsburgh starter Josh Fogg.
Fogg has been better than is 9-9 record. The right-hander is 3-1 with a 1.69 ERA over his last four starts. He has been solid since the All-Star break with a 2.58 ERA in nine starts.
The Pirates have lost two in a row and six of their last eight overall.