SAN DIEGO — As the ball flared toward right field, Eric Hosmer stopped in his tracks on his way to second base. Standing not far behind him, pitcher Archie Bradley watched Steven Souza Jr. charge in, and he imagines his thoughts weren’t too dissimilar to those of the San Diego Padres’ baserunner.

“His glove was up,” Bradley said, “and I’m like, ‘Oh, is this (going to be caught)?’”

It wasn’t. Souza knew it. But by making it look like there was a chance he might dive for the ball, Souza forced Hosmer to hold up, then fired a strike to second base for the force.

As it happened, that might have been the most important out of the day, a play that helped the Diamondbacks preserve a 5-4 victory on Sunday afternoon and finish off a three-game sweep of the Padres at Petco Park.

With the Los Angeles Dodgers falling in Atlanta earlier in the day, the Diamondbacks moved within a half-game of first place in the National League West.

The Diamondbacks more survived than prevailed on Sunday. They scored all of their runs on the strength of three swings, two-run homers by Paul Goldschmidt and Nick Ahmed and a solo shot by A.J. Pollock. After watching the Padres rally from a two-run deficit to tie the game in the third, the Diamondbacks jumped back in front and spent the rest of the day trying to hold the line.

Souza’s play helped them do that. After Hosmer led off the eighth with a single, Christian Villanueva flared a sinker from Bradley into right. Souza thought initially he might have had a chance at the ball, but realized soon enough it was going to fall.

“Once you get to a certain point, you kind of realize you’re not going to get it and you do whatever you can to freeze a runner and hold some ground,” Souza said. “It’s tough for (Hosmer) to make a read on that. Some of those balls topspin, some of them don’t. You don’t really know if they’re going to land. I have been on the other end and it’s not fun.”

Souza grabbed the ball on the bounce and uncorked a strong throw to second, with Ahmed stretching to make the catch. Hosmer was initially ruled safe, but the call was overturned after a replay review.

For Souza, who missed much of the season’s first three months due to a shoulder injury, it was the first time this year he had been able to change a game with his arm. He sounded as though he had almost forgotten how it felt.

“You guys think it looks all right now?” Souza asked reporters. “It feels good. It’s great. I’m excited to be a contributor on defense. For a while there, I felt like I was a liability all over the place.

“This is great. This is the way I love to play the game. Getting back to just being a part of the team and being who I am. That’s one part of my game that I love and that I’ve been blessed with. It’s been fun.”

Given the way the rest of the inning unfolded, Souza’s play turned out to be crucial. The next batter, Freddy Galvis, crushed a double of the left-field wall to score Villanueva, bringing the Padres within one at 5-4.

“If he doesn’t get that guy, who knows what’s going to happen,” Bradley said. “… Maybe two guys score there. He maybe saved the game.”

With a September schedule loaded with contending teams, the Diamondbacks appear to be at the beginning of a stretch of games in which they can “bank wins,” to borrow a favorite phrase of manager Torey Lovullo.

They did that with three victories against the Padres, and with series upcoming against the Texas Rangers, San Francisco Giants and Cincinnati Reds, plus another four-game set against the Padres, they’ll have more chances to beat up on teams with mediocre or losing records.

“We’ve got to keep it rolling,” Souza said. “Every series from here on out is huge. We’re looking to push it forward.”

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Reach Piecoro at (602) 444-8680 or [email protected]. Follow him on Twitter @nickpiecoro.