SCOTTSDALE, Ariz. -- Zac Gallen got his first look at hitters this spring when he tossed a live batting practice session on the backfields of the D-backs' Spring Training complex on Sunday.

Among the hitters who Gallen faced were Alek Thomas and Emmanuel Rivera.

Gallen, who is expected to be Arizona’s Opening Day starter, and No. 2 starter Merrill Kelly are being brought along slower than the team's other pitchers as a result of the workload the pair shouldered during last year’s run to the World Series.

Gallen, who threw combined 243 2/3 innings in the regular season and postseason, is not expected to get into a game situation until Friday. Kelly, who threw 201 2/3 innings in the regular season and postseason, will make his first Cactus League start on March 8.

“Just trying to work on my delivery, just make sure everything feels right,” Gallen said of what he got out of the session. “You know, you play catch and have all the great feels that you want, but when a hitter steps in the box, it’s a different adrenaline, different intensity.”

Feel is important to Gallen, who references that a lot after his regular-season starts, and he is constantly working to get to where the ball feels good coming out of his hand.

“I felt all right,” he said. “I mean, I still feel a little rushed, but that's just a timing thing. I think that just comes with time of getting used to seeing hitters again, just like not to be in a rush to get the ball over the plate. It's something I've been working on playing catch and I feel a lot better about it playing catch, now it’s just translate it to the mound. Obviously adding the slope and adding a hitter throws different variables in there.”

Gallen was on board with the organization when they approached him about going a little slower to start the spring. The right-hander, who finished third in the National League Cy Young Award voting last year, is at the point in his career where he knows what he needs to do and how he wants to feel before a season starts.

“I know that they're obviously trying to be smart about us,” Gallen said of himself and Kelly. “Just because we threw so much last year and it's like you want to be smart about the innings in Spring Training.”

Slade's slider impresses

Left-hander Tommy Henry and righty Ryne Nelson are considered to be the front-runners to nab the No. 5 spot in the rotation, but D-backs manager Torey Lovullo said Sunday not to forget about right-hander Slade Cecconi.

Cecconi made his big league debut for the D-backs last year, and aside from a rough start against the Orioles in which he allowed six runs in 3 1/3 innings, Cecconi acquitted himself well.

The 24-year-old appeared in seven games, four as a starter, and had a 4.33 ERA while also tossing a pair of scoreless innings in the National League Championship Series.

The one thing that Cecconi did not do was pitch deep into games as the D-backs seldom let him face the order a third time. During his brief time in the Majors in 2023, Cecconi faced only four batters for a third time.

“We're trying to figure out how to how to lengthen out his outings and [have him] be a better pitch maker the third time around the lineup,” Lovullo said. “That was his challenge.”

Part of that is a matter of refining his secondary pitches, something that Cecconi worked on in the offseason and saw pay dividends Sunday as he tossed two hitless innings while striking out four to one walk.

Cecconi felt good about his fastball, slider, curve and changeup and he was especially pleased with how hard he was able to throw his slider, hitting at least 87 mph twice on Sunday. Cecconi had an average slider velocity of 83 mph in 2023, but on Sunday, it was up to 85.2 mph.

“Last year, I was very slider heavy,” Cecconi said. “A lot of fastball/slider and the huge goal this offseason was to really develop a four pitch-mix. There's a there's a big point of emphasis from the coaches in the analytics department showing that when I throw [my slider] 85 [mph] and above there are much better numbers from my side of things. A lot less hard contact and more swing-and-miss, so there's a much greater emphasis on throwing it harder.”

Near no-no

The D-backs used six pitchers and allowed just two hits to the White Sox in their 5-0 win on Sunday. The first true hit came with one out in the ninth when pinch-hitter Oscar Colas singled. Chicago was awarded a second hit before game's end when the official scorer changed an eighth-inning error on third baseman Andrés Chaparro to a hit.