ST. LOUIS -- The Astros designated starting pitcher Armando Galarraga for assignment on Wednesday and brought up reliever Hector Ambriz to take his place on the roster.
Ambriz was signed as a Minor League free agent on June 21. He is 1-1 with a 3.33 ERA in 18 games at Triple-A Oklahoma City.
Interim manager Tony DeFrancesco plans to use Ambriz in a seventh- or eighth-inning setup role. DeFrancesco managed Ambriz at Oklahoma City.
"He's a good addition to our bullpen," DeFrancesco said. "He's a power arm, 92 to 95 [mph], with a nice breaking ball."
Ambriz made 34 appearances with the Cleveland Indians in 2010, going 0-2 with 5.59 ERA.
"I liked the way he competed," DeFrancesco said. "He shows the velocity we are looking for at this level."
Galarraga was 0-4 with a 6.75 ERA in five starts.
The departure of Galarraga, who was set to start on Saturday in New York, opens up a spot in the starting rotation. DeFrancesco said a decision will be made in the next couple of days.