As Patrick Corbin continues to find his form following Tommy John surgery, the Arizona Diamondbacks plan to remain cautious with someone they expect to be a key part of their future.

The left-hander hopes to have a more efficient outing than his last when he takes the mound in Sunday's decisive finale against the visiting Cincinnati Reds.

Corbin (2-3, 3.99 ERA) allowed three runs, six hits and walked two while throwing 54 pitches in only 1 1-3 innings before manager Chip Hale took him out of a 5-4 loss at Washington on Tuesday.

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''We're always going to err on the conservative side with him,'' Hale said. ''We almost didn't let him go out for the second."

Corbin completed at least five innings in each of his first five starts - and yielded two or fewer runs in four of them - since returning July 4 from elbow surgery.

"We have to be very careful - we want to get through 2015 healthy,'' Hale said. ''He's going to be our guy in '16, we know that. In '15, he's already proven in his six starts that he deserves to be that guy.''

A 14-game winner in 2013 who missed all last season, the 26-year-old Corbin understands the point of view of the Diamondbacks (53-56) as an organization.

"I know I'm going to be on a tight limit if I get into some trouble," he told MLB's official website.

Corbin is 1-1 with a 2.28 ERA in three starts against Cincinnati (49-59), which snapped a 30-inning scoreless drought to even this three-game set with Saturday's 4-1 victory. Brandon Phillips, Eugenio Suarez and Marlon Byrd each homered to help the Reds snap a three-game skid.

Though four Cincinnati players recorded two hits, All-Star third baseman Todd Frazier went hitless in four at-bats and is batting .104 with 16 strikeouts over the last 12 contests.

"It's just a matter of getting out of it quick," Frazier said. "Right now, it's a slow pace."

He's 2 for 9 with a double against Corbin.

Making his first career appearance against the Diamondbacks, Anthony DeSclafani (7-7, 3.71) is 2-0 with a 2.25 ERA in his last three starts. He yielded a two-run homer and struck out a career-high nine in six innings of Tuesday's 3-2 victory over St. Louis.

"He has good stuff and he trusts it," Reds manager Bryan Price said. "It's more attitude than anything. I don't think he has any fear.''

The right-hander won't face infielder Cliff Pennington, who was traded to Toronto for minor league shortstop Dawel Lugo prior to Saturday's contest. The deal came less than 24 hours after the Diamondbacks sent reliever Oliver Perez to Houston.

Despite sitting 8 1/2 games out of first in the NL West, eight back of the final wild-card spot and jettisoning a pair of veterans, the Diamondbacks aren't giving up.

"Our goal has not changed," Hale said. "We're going to sprint it to the finish and we're going to battle every night to win."

Paul Goldschmidt no longer leads the majors in batting after his average dropped to .332 while going 3 for 27 with 12 strikeouts in seven games this month.

''We always count on him to be that guy but it is not that easy to do all the time," Hale said. "They are pitching him pretty well."