MESA, Ariz. -- Jackson Merrill started two of the Padres’ first three games this spring, doing so while learning a new position defensively. For most players at this stage of camp, Sunday would have been a natural off-day.

Not Merrill. The Padres bused across the Valley to face the Cubs in Mesa on Sunday, and Merrill was atop their lineup, serving as the designated hitter.

Fine by him.

• The player on each team with the most to prove in Spring Training

“It’s so fun coming out here,” Merrill said after the Padres’ 7-0 victory, their first in Cactus League play. “I could sleep here, if I’m being honest.”

The real reason Merrill was atop the lineup on Sunday? The Padres want a good, long look at their No. 2 prospect in the MLB Pipeline rankings. He is vying for a spot on the roster and perhaps in the Opening Day lineup. They want him facing as much quality big league-caliber pitching as possible.

So far, so good.

In his first at-bat Sunday, the left-handed-hitting Merrill found himself behind in the count against Cubs righty Javier Assad. He worked it even at 2-2, then laced a double to the opposite field. An inning later, Merrill shot a two-run single through the left side.

Perhaps his most impressive plate appearance came in the fourth inning against Cubs reliever Edwin Escobar. Merrill worked a full count, then laid off a left-on-left slider to earn a walk.

A career shortstop, Merrill is learning left field on the fly this spring. He has been tested quite a bit there already, and he’s made a couple sparkling plays. Quickly, it’s becoming clear that the Padres aren’t concerned about Merrill’s glove.

Sure, there might be some growing pains in left. But he’s probably good enough defensively -- and bound to get better. In other words, if Merrill can prove it at the plate, he’ll be on the roster.

And therein lies the challenge. Merrill has played only 46 games at Double-A, where he posted a .782 OPS last season. He has faced little upper-level pitching. But the early returns are impressive.

“It’s just baseball man,” Merrill said. “Everybody’s got good pitches, everybody knows how to work you, pitch you different days. But it’s just baseball at the end of the day. … In the box, I feel like I own the count, and I own the at-bat.”

Merrill will continue to get reps at short this spring, manager Mike Shildt said. Merrill is a high-ceiling 20-year-old shortstop prospect, after all. The Padres don’t want that skill set to wither.

But right now, the San Diego infield is set -- with more than enough options at short. In left field, there’s a vacancy.

And one of the sport’s top prospects might just be ready to seize it.

Azocar stakes his claim
It’s a tight battle for places in the outfield. But José Azocar entered camp with a leg up, in one sense: He already has proven to the Padres that he can come off the bench and serve as a useful fourth or fifth outfielder.

Still, Azocar will need to win his place this spring. And he took a step toward that end on Sunday, going 2-for-2 with a double and a home run. Power certainly hasn’t been Azocar’s calling card; it took 289 plate appearances before his first big league home run last September. But Shildt sees more power potential for Azocar, if he’s swinging at the right pitches.

“That was a loud noise,” Shildt said of the home run. “He’s swinging the bat well, going about it well. He’s been really intentional about his plate-zone discipline, and it’s starting to show up in the game. [He’s] getting more strikes, and he’s got a nice stroke, got some pop. It’s good to see.”

Young starters shine
Making his Cactus League debut, Randy Vásquez, one of the four right-handers acquired from the Yankees in the Juan Soto trade, looked like the electric, high-upside arm the Padres thought they were acquiring. Vásquez was a bit erratic at first, walking a pair in the first inning. But he pitched two scoreless, hitless frames while striking out two.

“Pretty crisp -- ball came out really good, looked like some good movement,” Shildt said.

Vásquez is one of the primary contenders for a spot at the back of the Padres’ rotation. Meanwhile, Drew Thorpe and Adam Mazur, the team’s No. 6 and No. 8 prospects, respectively, seem destined to start the year in the Minors. But both were solid on Sunday, pitching a scoreless inning apiece.