"I got the call up yesterday, got on the road and drove up here last night," he said on Sunday afternoon, before the Cardinals played the Cubs.
Parisi was scheduled to start for Memphis on Sunday, but will likely be on call for long relief of starter Todd Wellemeyer on Sunday or for Joel Pineiro on Monday at Colorado.
"There's no real plan," Parisi said. "They need innings. I'm still longed out, from being a starter, to get some innings. I can come in for an inning, or I can come in for an out or start. It's kind of up in the air."
The 25-year-old Parisi, who was selected in the ninth round (270th overall) of the 2004 Draft, has not made a Major League appearance in his young career. He went 9-8 with a 4.60 ERA at Double-A Springfield in 2006, and was 8-13 with a 4.91 ERA at Memphis in 2007.
"There's been a lot of learning, a lot of great pitching coaches," Parisi said of his road to the big leagues. "I had a great pitching coach in college. I've hit every level and at every level I took something or some levels I took a whole lot. Low A I really focused on throwing inside. In college, everything is away, away, away. And then every level I hit I just learned a little bit more. This was my second big league camp this year. I got to come in and learn a lot from those guys and try to make an impression on the staff. That's all I could really do."
A 6-foot-3, 215-pounder, Parisi was 2-1 with a 4.44 ERA in six starts in Memphis this season, though his ERA jumped up from 3.00 after getting beat up in his last outing against Salt Lake when he was charged with seven earned runs in four innings.
"What he showed was when we called down there, he was the guy they recommended," Cardinals manager Tony La Russa said on Sunday. "He's showed a Major League arm, Major League stuff. He was excited early and kind of all over the place. Progressively, he just settled in. That was impressive."
Reyes, 26, was 1-1 with one save and a 5.27 ERA in nine games. In 13 2/3 innings, he allowed eight earned runs on 16 hits while striking out 10 and walking three. Reyes tossed two shutout innings in relief on Saturday in the 9-3 Cardinals loss.
Reyes went 5-8 with a 5.06 ERA in 17 starts in 2006, and then struggled to a 2-14 mark with an ERA of 6.04 in 22 games, including 20 starts, in 2007.
"I don't think he was happy," La Russa said. "He's been through this before. He just said, 'OK.' He didn't pout or slam the door. He would prefer to be in the big leagues."
Nate Latsch is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.