Matt Garza landed on the 15-day disabled list Tuesday but the veteran right-hander is confident that his strained left oblique won't be nearly as big of a problem as it was last season, when he was sidelined nearly seven weeks.

"I have more range of motion, it's easier doing things every day -- breathing, coughing, waking up, rolling out of bed," Garza said Tuesday. "It's a lot easier than it was last year."

Garza suffered the injury Sunday afternoon at St. Louis. He was dominating the Cardinals through five innings and allowed just one hit. But with two outs in the sixth, he felt a grab on his second-to-last pitch of the inning and gave way to a pinch-hitter in the seventh.

The injury came in the midst of one of Garza's best stretches this season. In his last three starts, Garza is 1-0 and has allowed just 21 innings of work.

Take out a dreadful appearance on July 19, when he allowed five first-inning runs and recorded only one out, and Garza is 5-1 with a 1.95 ERA over his last 12 starts.

"I don't like it, but I understand it," Garza said. "Being competitive, you don't want to come here and not do anything. You want to feel like you're doing stuff. Best thing for me is kind of just take a step back and kind of get away from myself. That's the best thing."

Roenicke said he's optimistic that Garza will be ready to return on Aug. 19.

"We'll look at it like it is just going to be the 15 days, but we'll determine that as we go on," Roenicke said. "He won't pick up a ball or throw it for a while. He'll do some stuff inside, some plyos inside and keep his arm active. These things are hard to tell. Obliques sometimes last longer than you think. He says he doesn't think he did it bad. Hopefully that's the case."

Garza's next turn in the rotation is Saturday against the Dodgers. Roenicke wasn't ready to divulge who will make that start.

He brushed off a radio host's assumption that Marco Estrada, who moved to the bullpen when right-hander Jimmy Nelson was called up from Triple-A Nashville, would return to the rotation and acknowledged that Mike Fiers, currently 8-5 with a 2.55 ERA in 17 starts for Nashville, was in consideration.

"We'll have to see how these games go," Roenicke said.

Signed over the winter to a four-year, $50 million contract, Garza has made 23 starts and is 7-7 with a 3.58 ERA.