The St. Louis Cardinals called up right-handed pitcher P.J. Walters from Triple-A Memphis and activated catcher Gerald Laird from the disabled list Thursday.
Pitcher Brandon Dickson and first baseman Mark Hamilton were sent to Memphis to make room on the roster.
Walters was 7-4 with a 4.27 ERA in 17 starts at Memphis. He has been with the Cardinals the past two seasons going 2-0 with a 7.24 ERA in 15 major- league appearances.
Laird missed 40 games because of a fractured index finger suffered May 22 in Kansas City.
Dickson did not allow a run in two appearances with St. Louis. Hamilton was hitting .182. He drove in the run in the Cardinals' 1-0 victory over Cincinnati on Monday.
St. Louis manager Tony La Russa said Laird, who was not in the starting lineup Thursday, will start at least one of the games in the four-game series with Arizona.