The Houston Astros named Tony DeFrancesco interim manager on Sunday after firing Brad Mills late Saturday night.
DeFrancesco had been managing Houston's Triple-A affiliate, the Oklahoma City RedHawks.
The Astros announced following a 12-4 loss to the Arizona Diamondbacks that they were relieving Mills, hitting coach Mike Barnett and first base coach Bobby Meacham of their duties.
General manager Jeff Luhnow appointed Ty Van Burkleo hitting coach and Dan Radison first base coach, both on an interim basis.
The Astros have the worst record in the majors this season.
"The goal is to find the best staff we can possibly assemble to take us to the next level," said Luhnow. "We want to move forward and win as many games as we can the rest of this year and put ourselves in a position to have a successful 2013 and beyond."
Mills was in the final year of a three-year contract that had a club option for 2013. He went 171-274 in as manager of the Astros, who lost a club-record 106 games last year.