"I concentrated," Whittaker said. "I knew I could do it."
Ulrich drove in two more runs with a single past the drawn-in infield, giving the Pirates a 3-0 lead.
Garrett Deutsch led off the game with a bunt single for the Astros. Sammy Borkton had a one-out single to put runners at first and second, but the team's only scoring opportunity never materialized.
Borkton struck out six batters and Erik Rasmussen had the Astros' other hit.
In Minor B action Monday: The Rockies defeated the Dodgers, 23-1, to force a deciding game Wednesday at TeWinkle at 5:15 p.m.