Matzek will start Wednesday's game against Atlanta in his major league debut.
Matzek is the fifth Rockies pitcher to make his major league debut this season and the third in a six-day span. Eddie Butler started Friday's game against the Dodgers and Christian Bergman made his debut in Monday's series opener against the Braves.
Butler has been placed on the 15-day disabled list with right rotator cuff inflammation.
Matzek, the 11th pick in the 2009 draft, was 5-4 with a 4.05 ERA in 12 starts for Colorado Springs this year.
Bettis was recalled Monday and he allowed three runs on four hits in one inning against Atlanta on Tuesday.