Berkman, who was held out of Friday's game, took batting practice in the cage and on the field prior to Saturday's game. Before taking his swings, Berkman said he was making progress with his injury.
"It feels a little better," he said. "It still feels like I have a charley horse in my calf, but I don't think it's as bad as it was yesterday, so I'm hopeful."
Berkman leads the team in nearly every offensive category but doesn't want to rush himself back into the lineup with three crucial games looming against the National League Central-leading St. Louis Cardinals beginning Monday.
"I'd like to play as soon as I can, but it's hard to say," Berkman said. "If it improves as much between now and tomorrow as it did between yesterday and today, there's a decent chance I could play tomorrow. It still doesn't feel like it should. It's an aggravation more than anything else."
With Berkman out of the lineup, Chris Coste made his first start at first base for the Astros.
Brian McTaggart is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.