GOODYEAR, Ariz. -- Reds rookie Aroldis Chapman threw his second bullpen session of the week Saturday and said he is starting to feel more comfortable each time he goes out on the mound.

"Today was really good. It went fine," Chapman said. "I think the week is getting better as it goes."

Chapman primarily threw four-seam fastballs during his 10-minute session but also mixed in a few sliders, changeups and two-seam fastballs. Veteran catcher Corky Miller caught Chapman's session Saturday. Ramon Hernandez caught Chapman's first bullpen session Thursday.

Class A Dayton pitching coach Tony Fossas and Reds pitching coach Bryan Price stood behind Chapman during the session.

"Everybody knows about his power and everybody knows that he has to work on his command," Miller said. "Today was a command day, where he was going to try to throw it over the plate. I don't know how hard he is throwing. It's hard to tell when a guy is around the zone."

Overall, Chapman said he did not feel as strong as he felt Thursday but is pleased with the progress he is making. He is working on his mechanics, which is normal for pitchers at this point of the season.

"Nobody here is in midseason form," Price said. "He was missing down and away to the left-handed hitters because his shoulder would come open and he'd carry the ball to that side of the plate. But it's a quick adjustment and he understands right away what he needs to do. His aptitude is also what makes him special beyond just his ability to throw the ball."

Chapman will get another chance to show his stuff soon. He is scheduled to throw another bullpen Monday and face live hitters on Wednesday and Saturday. After facing live hitters, he'll likely throw at least one more bullpen before pitching in a game.

"What I'm looking forward to is watching him face live hitters and seeing how he goes about his business and the adjustments he makes when needed," Price said. "I want to see how he handles the running game and anything that happens in a game."

Chapman will be ready.

"I'm feeling a lot more comfortable here," he said. "I'm getting to know my teammates and getting closer to them."