Jason Castro hit a three-run homer in the seventh inning and the Houston Astros beat fading Pittsburgh 4-1 Saturday night, handing the Pirates their fifth straight loss.

The Pirates fell 6½ games behind St. Louis for the last NL wild-card spot. Pittsburgh has lost 17 of its last 21 and dropped to 74-77, moving closer to its 20th straight losing season.

Rookie Dallas Keuchel (3-7) pitched seven strong innings for the win.

Castro hit his third home run of the season, connecting for a tiebreaking shot off Kevin Correia (11-10).

Pittsburgh manager Clint Hurdle was ejected in the second inning for arguing a call at first base.